# Practice Quiz

By rawrr183
Oct 09, 2014
5122 Words

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

1

This print-out should have 59 questions.

Multiple-choice questions may continue on

the next column or page – ﬁnd all choices

before answering.

face of the table? Assume the boxes each

have masses of 2.0 kg, the coeﬃcient of static

friction is µs between table and box, and the

acceleration due to gravity is 10 m/s2 .

001 10.0 points

A block accelerates 3 m/s2 down a plane inclined at angle 27.0◦. The acceleration of gravity is 9.81 m/s2 .

1. The force of the static friction would have

a vertical component in this situation, and

that is impossible since it must be parallel to

the table surface.

2

3

s

m/

2. 20 N

3. Very small, almost zero

m

µk

27◦

4. 2.5 N

5. 5.0 N

Find µk between the block and the inclined

plane.

1. 0.166

6. fs would have to be greater than 20 N,

which is physically impossible, so this is not a

realistic situation.

7. 10 N

2. 0.148

8. Impossible to say from the information

given.

3. 0.510

003

4. 0.853

10.0 points

A block with an initial velocity v0 slides up

and back down a frictionless incline.

5. 1.289

002

10.0 points

Two identical boxes are connected by a

string of negligible mass, which runs across a

frictionless peg. One box is on a horizontal

table, while the other box hangs vertically.

If the hanging box is released from rest, it

remains at rest.

m

m

What must be the force of static friction

between the box on the table, and the sur-

v0

θ

Which graph best represents a description

of the velocity of the block versus time? The

initial position of the block is the origin;

i.e., x = 0 at t = 0 . Consider down the track

to be the positive x-direction.

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

v

v

t

1.

2

t

8.

v

v

t

2.

t

9.

v

t

3.

v

10.

t

v

t

4.

v

t

5.

004 10.0 points

If a car hits a tree, the car’s occupants (if

the car has no seat belts or air bags) will be

violently accelerated forward and strike the

dashboard with murderous force, due to an

initial forward force exerted on their bodies

by the backs of their seats.

1. False

2. None of these

v

t

6.

3. This may happen in a few cases, but it is

very rare.

4. True

5. This may happen in many cases, but not

in every case.

v

7.

t

005 (part 1 of 5) 10.0 points

A car travels at a speed of 30 m/s around a

curve of radius 69 m.

The acceleration of gravity is 9.8 m/s2 .

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

3

In this case, which of these two forces has

the smaller magnitude?

1. m g

1. 9

g

M

2. None of these

µ

36◦

3. Both have the same magnitude.

4. n

5. If a is downward, n = 0 .

What is the net centripetal force needed to

keep the car from skidding sideways?

Answer in units of N

006 (part 2 of 5) 10.0 points

Were there no friction between the car’s tires

and the road, what centripetal force could be

provided just by the banking of the road?

Answer in units of N

007 (part 3 of 5) 10.0 points

Now suppose the friction force is suﬃcient to

keep the car from skidding. Calculate the

magnitude of the normal force exerted on the

car by the road’s surface. Hint: Check the

correctness of your answer to the ﬁrst question

before proceeding with this and the following

questions.

Answer in units of N

008 (part 4 of 5) 10.0 points

Calculate the magnitude of the friction force.

Answer in units of N

009 (part 5 of 5) 10.0 points

Calculate the lowest possible value of the

static friction coeﬃcient µs that would prevent the car from skidding. 010 10.0 points

Consider a person standing in an elevator that

is moving at constant speed upward. The

person, of mass m, has two forces acting upon

him, the downward force m g due to gravity,

and the upward supporting force n exerted by

the ﬂoor of the elevator.

6. If a is downward, mg = 0 .

011 (part 1 of 3) 10.0 points

Consider a loop-the-loop system where the

radius of the loop is R. A small block (of

negligible size) is released from rest at the

1

point P , which is at a height of 4 R.

8

m

P

33

R

8

C

R

B

A

What is the kinetic energy KB at B? Friction between the block and the track is negligible. 19

mgR

5

18

2. KB =

mgR

5

31

mgR

3. KB =

8

25

4. KB =

mgR

8

1. KB =

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

5. KB =

16

mgR

5

2. NA =

6. KB =

11

mgR

5

3. NA =

7. KB =

26

mgR

7

4. NA =

8. KB =

19

mgR

7

5. NA =

9. KB =

17

mgR

7

6. NA =

10. KB =

19

mgR

8

7. NA =

012 (part 2 of 3) 10.0 points

What is the tangential speed vC at C?

8. NA =

9. NA =

37

mg

5

23

mg

2

27

mg

4

39

mg

4

35

mg

4

73

mg

7

45

mg

4

55

mg

7

37

mg

4

1. vC =

16

gR

5

2. vC =

34

gR

7

3. vC =

38

gR

7

4. vC =

12

gR

5

5. vC =

17

gR

4

1. Twice as far

6. vC =

8

gR

3

2. Half as far

7. vC =

23

gR

4

8. vC =

20

gR

7

10. NA =

014 10.0 points

Car B has the same mass as Car A but is

going twice as fast.

If the same constant force brings both cars

to a stop, how far will car B travel in coming

to rest as compared to the distance car A

traveled?

3. Eight times as far

4. Three times as far

5. None of these

9. vC =

27

gR

4

6. The same distance

10. vC =

11

gR

2

7. A quarter as far

013 (part 3 of 3) 10.0 points

What is the force NA with which the track

pushes up on the block at the point A (at the

bottom of the loop)?

21

1. NA =

mg

2

4

8. Insuﬃcient information is given.

9. Four times as far

015

10.0 points

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

A ball of mass M is suspended by a thin

string (of negligible mass) from the ceiling

of an elevator. The vertical motion of the

elevator as it travels up and down is described

in the statements below. Indicate for each of

the situations described the relation between

value of the tension T in the string and the

weight of the ball M g, or whether one cannot

tell.

T

v

M

Elevator

with a

weight

held by

a string

inside it

5

block is 9.78 kg and the acceleration of gravity

is 9.8 m/s2 .

Answer in units of m/s2

017 10.0 points

A balloon of mass M is ﬂoating motionless in

the air. A person of mass less than M is on

a rope ladder hanging from the balloon. The

person begins to climb the ladder at a uniform

speed v relative to the ground.

How does the balloon move relative to the

ground?

1. Up with a speed less than v

2. Down with speed v

3. Down with a speed less than v

The elevator is traveling upwards and its

upwards velocity is increasing as it starts towards a higher ﬂoor. 1. T < M g

2. T = M g

3. T > M g

4. Cannot be determined.

016 10.0 points

The block is released from rest on the incline

with the spring initially unstretched:

78.2 N/m

x

8

9. 7

5. Up with speed v

018 10.0 points

Two carts are put back-to-back on a track.

Cart A has a spring-loaded piston; cart B,

which has twice the inertial mass of cart A, is

entirely passive. When the piston is released,

it pushes against cart B, and the carts move

apart.

How do the magnitudes of the ﬁnal momenta p and kinetic energies K compare? 1. pA = pB , KA > KB

2. pA < pB , KA = KB

3. pA < pB , KA < KB

4. pA > pB , KA > KB

kg

µ=

4. The balloon does not move.

0

30◦

5. pA > pB , KA < KB

6. pA = pB , KA < KB

Choosing down the incline as the positive

direction, what is its acceleration at its lowest

point? The angle of inclination is 30 ◦ , the

spring constant is 78.2 N/m the mass of the

7. pA = pB , KA = KB

8. pA > pB , KA = KB

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

9. pA < pB , KA > KB

019 10.0 points

Two blocks of masses M and 3M are placed

on a horizontal, frictionless surface. A light

spring is attached to one of them, and the

blocks are pushed together with the spring

between them.

3M

M

Before

(a)

v

impact lifts the block 0.23 m up. (That is, the

block — with the bullet stuck in it — rises

0.23 m up above its initial position, and then

falls back down.)

Given g = 9.8 m/s2 . What was the initial

velocity of the bullet?

Answer in units of m/s

021 (part 1 of 2) 10.0 points

Consider the 693 N weight held by two cables

shown below. The left-hand cable had tension T2 and makes an angle of 54 ◦ with the ceiling. The right-hand cable had tension T1

and makes an angle of 50◦ with the ceiling.

3M

M

54 ◦

◦

50

The two blocks are at rest ﬁrst. Then the

cord holding them together is burned, after

which the block of mass 3M moves to the

right with a speed of 2 m/s. What is the

speed of the block of mass M?

1. 0 m/s

T1

T2

After

(b)

6

693 N

a) What is the tension in the cable labeled

T1 slanted at an angle of 50◦ ?

Answer in units of N

022 (part 2 of 2) 10.0 points

a) What is the tension in the cable labeled T2

slanted at an angle of 54◦ ?

Answer in units of N

2. 6 m/s

3. 2 m/s

4. impossible to determine

5. 1.5 m/s

6. 0.67 m/s

7. 4 m/s

020 10.0 points

A 11.7 g bullet is ﬁred vertically into a 1.65 kg

block of wood.

023 10.0 points

You are given two carts, A and B. They look

identical and you are told that they are made

of the same material. You place A at rest on

an air track and give B a constant velocity directed to the right so that it collides elastically with A. After the collision, both carts move

to the right, the velocity of B being smaller

than what it was before the collision.

What do you conclude?

1. Cart A is hollow.

v0

The bullet gets stuck in the block, and the

2. need more information

3. Cart B is hollow.

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

4. The two carts are identical.

1. 0.2

024 10.0 points

You are on a rooftop and you throw one ball

straight down and another straight up. The

second ball, after rising, falls and also strikes

the ground below.

If air resistance can be neglected and if your

downward and upward initial speeds are the

same, how will the speed of the balls compare

upon striking the ground?

1. They have same speed.

2. The speed of the second ball is smaller

than that of the ﬁrst one.

3. The speed of the second ball is larger than

that of the ﬁrst one.

2. 0.05

3. 20

4. 2

5. 0.5

027 10.0 points

On the surface of the earth is a pendulum of

mass m and length ℓ.

If the pendulum is allowed to swing down

from rest starting from an initial horizontal

position, with the forces acting being T, the

tension in the string, and m g , the force of

gravity, how much work has been done on the

pendulum as it swings through the vertical

position?

4. More information is needed

1. m g +T times

025 10.0 points

A block starts at rest and slides down a frictionless track except for a small rough area on a horizontal section of the track (as shown in

the ﬁgure below).

It leaves the track horizontally, ﬂies through

the air, and subsequently strikes the ground.

The acceleration of gravity is 9.81 m/s2 .

9.81 m/s2

2.2 m

h

v

1.2 m

µ=0.2

4.15 m

At what height h above the ground is the

block released?

Answer in units of m

026 10.0 points

A horizontal force of 100 N is used to pull a

crate, which weighs 500 N, at constant velocity across a horizontal ﬂoor. What is the coeﬃcient of kinetic friction?

π

ℓ, the distance traveled.

2

2. T ℓ

3. m g ℓ, with the pendulum’s KE increasing

by this amount.

4. Zero; energy is conserved.

028

512 g

7

10.0 points

A 7 kg mass slides to the right on a surface

having a coeﬃcient of friction 0.15 as shown.

The mass has a speed of 4 m/s when contact is

made with a spring that has a spring constant

101 N/m. The mass comes to rest after the

spring has been compressed a distance d. The

mass is then forced toward the left by the

spring and continues to move in that direction

beyond the unstretched position. Finally the

mass comes to rest a distance D to the left of

the unstretched spring.

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

v

101 N/m

7 kg

4 m/s

7 kg

d

v⊃ = 0

8

How long does it take Tperiod for the ball to

rotate once around the axis?

Answer in units of s

031 10.0 points

A block is at rest on the incline shown in the

ﬁgure. The coeﬃcients of static and kinetic

friction are µs = 0.6 and µk = 0.51, respectively.

The acceleration of gravity is 9.8 m/s2 .

7 kg

43

vf

kg

µ

28◦

7 kg

v⊢ = 0

7 kg

101 N/m

D

µ = 0.15

Find the compressed distance d. The acceleration of gravity is 9.8 m/s2 . Answer in units of m

029 (part 1 of 2) 10.0 points

A small metal ball is suspended from the ceiling by a thread of negligible mass. The ball is then set in motion in a horizontal circle so

that the thread describes a cone.

The acceleration of gravity is 9.8 m/s2 .

What is the frictional force acting on the

43 kg mass?

Answer in units of N

032 10.0 points

Two crates are touching, resting on a practically frictionless surface. If you apply a force F with your hand against the larger crate

of mass M , both crates accelerate across the

surface, and remain in contact.

a

F′

F

M

m

Which statement is wrong?

◦

20

9.8 m/s2

1. The force F ′ = −m a.

1. 8

m

v

5.1 kg

What is the speed of the ball when it is in

circular motion?

Answer in units of m/s

030 (part 2 of 2) 10.0 points

2. The smaller crate exerts a force F ′ backward on the larger crate, equal and opposite to the force (not shown) that the larger crate

exerts forward on the smaller one to accelerate it.

3. The forces F and F ′ are equal and opposite, as required by Newton’s third law. 4. The magnitude of the acceleration of the

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

F

, where F

M +m

is the magnitude of F and m is the mass of

the smaller crate.

two crates will be given by

033 10.0 points

Five ramps lead from the ground to the second

ﬂoor of a workshop, as sketched below. All

ﬁve ramps have the same height; ramps B,

C, D and E have the same length; ramp A is

longer than the other four. You need to push

a heavy cart up to the second ﬂoor and you

may choose any one of the ﬁve ramps.

9

034 10.0 points

A box is attached to an unstretched spring

of force constant k and rests on a horizontal

tabletop. The box is moved out to the right

a distance ℓ along the table, stretching the

spring, and released. It remains at rest when

released.

k

m

ℓ

A

B

C

What is the force of static friction in this

situation?

1. fs = µs m g to the right.

2. fs = k ℓ to the right.

D

3. fs = k ℓ to the left.

E

Assuming no frictional forces on the cart,

which ramp would require you to do the least

work?

1. Unable to determine without knowing the

exact proﬁles of ramps C, D or E.

2. Ramp D.

3. Same work for all ﬁve ramps.

4. Ramp B.

5. Ramp A.

6. Same work for the straight ramps A and

B; less work for ramps C, D, and E.

7. Same work for ramps B, C, D or E; more

work for ramp A.

8. Ramp C.

9. Ramp E.

4. fs = µs m g to the left.

035 10.0 points

A bowling ball is hanging in mid-air at rest

in a room on board the International Space

Station. An astronaut throws a golf ball directly at the bowling ball, and they collide elastically.

Compared to its values before the collision,

the golf ball after the collision has a

1. All of these

2. momentum that has changed from p to

roughly −p .

3. slightly less momentum.

4. slightly less kinetic energy.

5. None of these

036 10.0 points

Static friction 0.49 between a 0.9 kg block

and a 3.9 kg cart. There is no kinetic friction

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

F

3.9 kg

µ = 0.49

9.8 m/s2

between the cart and the horizontal surface.

The acceleration of gravity is 9.8 m/s2 .

10

3.27 m

0.9 kg

What minimum force F must be exerted on

the 3.9 kg cart in order for the 0.9 kg block

not to fall?

What minimum coeﬃcient of friction between a rider’s clothing and the wall of the cylinder is needed to keep the rider from

slipping? The acceleration due to gravity

is 9.81 m/s2 .

1. F = 91 N

2. F = 76 N

3. F = 94 N

038 10.0 points

A 4.2 kg block is pushed along the ceiling with

a constant applied force of 80 N that acts at

an angle of 56◦ with the horizontal. The block

2

accelerates to the right at 5.4 m/s2 .

4. F = 77 N

µ

5. F = 96 N

4.2 kg

6. F = 49 N

5.4 m/s2

80

7. F = 66 N

N

◦

56

8. F = 70 N

9. F = 68 N

10. F = 74 N

037 10.0 points

In a popular amusement-park ride, a cylinder of radius 3.27 m is set in rotation at an angular speed of 5.36 rad/s, as shown in the

ﬁgure. The ﬂoor then drops away, leaving the

riders suspended against the wall in a vertical

position.

What is the coeﬃcient of kinetic friction

between the block and the ceiling? The acceleration due to gravity is 9.81 m/s2 . 039

10.0 points

A box of mass M is being accelerated up a

vertical wall by a constant force F applied at

an angle θ with the vertical, as shown.

a

M

F

θ

µk

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

If the coeﬃcient of kinetic friction between

the box and wall is µk , what is the magnitude

of the acceleration of the box?

F

from Newton’s Second Law

M

F

(cos θ − µk sin θ) − g

2. a =

M

F sin θ

3. a =

M

1. a =

4. a = µk g

F

(sin θ − µk cos θ) + g

M

F

(cos θ + µk sin θ) − g

6. a =

M

F sin θ

7. a = g −

M

F

8. a =

−g

M

F

(sin θ − µk cos θ) − g

9. a =

M

11

Find the speed of the bullet. The acceleration due to gravity is 9.81 m/s2 . Answer in units of m/s

041 10.0 points

A pendulum made of a string and a sphere

is able to swing in a vertical plane. The

pendulum is released from a position of 70 ◦

from vertical as shown in the ﬁgure below.

The string hits a peg located a distance d

below the point of suspension and rotates

about the peg.

The acceleration of gravity is 9.8 m/s2 .

5. a =

10. a = 0 since kinetic friction makes the box

slide at constant velocity

040

◦

33

2.8 m

vi

5.2 kg

d

70 ◦

9.8 m/s2

Find the smallest value of d (highest peg

position) in order for the sphere to swing in a

full circle centered on the peg.

Answer in units of m

10.0 points

A bullet of mass 3 g is ﬁred into the bob of

a ballistic pendulum of mass 5.2 kg. When

the bob is at its maximum height, the strings

make an angle of 33 ◦ with the vertical. The

length of the pendulum is 2.8 m.

3g

m

7 kg 10

vf

042 10.0 points

Note: The pendulum bob is released at a

height below the height of the peg.

A pendulum made of a string of length

10.5 m and a spherical bob of mass 7.3 kg

and negligible raius swings in a vertical plane.

The pendulum is released from an angular

position 39 ◦ from vertical as shown in the

ﬁgure below. The string hits a peg located

a distance 6 m below the point of suspension

and swings about the peg up to an angle α

on the other side of the peg. Then, the bob

proceeds to oscillate back and forth between

these two angular positions.

The acceleration of gravity is 9.8 m/s2 .

7.3 kg

39 ◦

α

9.8 m/s2

What is the maximum angle α which the

pendulum will swing to the right after hitting

the peg as shown above?

Answer in units of ◦

043 10.0 points

Consider the acceleration of block with

mass m across the frictionless table towards

the pulley.

Case I

m

In case I a block of mass m is attached to

the end of the string.

m

Case II

vx

1.3 m

µ=0.3

∆x

What is the speed v of the block when it

leaves the track?

Answer in units of m/s

045 (part 2 of 3) 10.0 points

What is the horizontal distance x the block

travels in the air?

Answer in units of m

046 (part 3 of 3) 10.0 points

What is the total speed of the block when it

hits the ground?

Answer in units of m/s

mg

In case II a force of m g is acts on the end

of the string.

The acceleration of block m is

1. greater in case I.

8.1 kN/m 501 g

5.3 cm

m

12

044 (part 1 of 3) 10.0 points

A block is pushed against the spring with

spring constant 8.1 kN/m (located on the lefthand side of the track) and compresses the spring a distance 5.3 cm from its equilibrium

position (as shown in the ﬁgure below).

The block starts at rest, is accelerated by

the compressed spring, and slides across a

frictionless track except for a small rough area

on a horizontal section of the track (as shown

in the ﬁgure below).

It leaves the track horizontally, ﬂies through

the air, and subsequently strikes the ground.

The acceleration of gravity is 9.8 m/s2 .

2.3 m

10

.5

m

6m

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

047 (part 1 of 2) 10.0 points

A wooden block hangs on a string. A bullet

hits and sticks in the block.

What is conserved in the collision of the

bullet with the block?

1. neither momentum nor mechanical energy

2. greater in case II.

2. momentum and mechanical energy

3. the same in both cases.

3. only mechanical energy

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

13

A

4. only momentum

048 (part 2 of 2) 10.0 points

After the bullet collides and sticks in the

wooden block that hangs on a string, the

block swings out from its lowest position and

reaches its highest position.

What is conserved in the motion after the

bullet has collided with the block and the

block swings up to the highest position?

1. momentum and mechanical energy

2. neither momentum nor mechanical energy

3. only momentum

4. only mechanical energy

049 (part 1 of 2) 10.0 points

Consider the 40 N weight held by two cables

shown below. The left-hand cable is horizontal.

◦

43

40 N

a) What is the tension in the cable slanted

at an angle of 43◦ ?

Answer in units of N

050 (part 2 of 2) 10.0 points

b) What is the tension in the horizontal cable?

Answer in units of N

051 10.0 points

Consider a frictionless roller coaster such as

depicted.

C

hA

16 m

B

Passenger cars start at point A with zero

initial speed, accelerate as they go down to

point B, swing around the circular vertical

loop B → C → B of radius 16 m, then go

on towards further adventures (not shown).

When a car goes through the top of the loop

(point C), the passengers feel weightless (for

just a moment).

What is the height hA of the starting

point A above the loop’s bottom B? The acceleration of gravity is 9.8 m/s2 . Answer in units of m

052 10.0 points

Consider a loop-the-loop system where the

radius of the loop is R. A small block (of

negligible size) is released from rest at the

4

point P , which is at a height of 4 R.

5

m

P

24

R

5

C

R

B

A

What is the force NA with which the track

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

pushes up on the block at the point A (at

the bottom of the loop)? Consider friction

between the block and the track to be negligible.

1. NA =

2. NA =

3. NA =

4. NA =

5. NA =

53

mg

5

65

mg

7

47

mg

5

21

mg

4

33

mg

4

14

054 10.0 points

Which of these systems is NOT an “isolated

system” to which conservation of momentum

can be applied?

1. A ball falls freely toward the ﬂoor. (Ignore

air friction.) System: the ball

2. Two masses connected by a spring oscillate on a frictionless tabletop. System: the two masses and the spring

3. A ball falls freely toward the ground.

(Ignore air friction.) System: the ball and the

earth

6. NA = 12 m g

7. NA =

8. NA =

9. NA =

10. NA =

31

mg

3

49

mg

5

35

mg

4

41

mg

5

053 10.0 points

Consider a frictionless track as shown in the

ﬁgure.

A block of mass 3.411 kg is released on

the track at a height 5.08 m above the level

surface. It slides down the track and makes a

head-on elastic collision with a block of mass

6.822 kg, initially at rest.

The acceleration of gravity is 9.8 m/s2 .

5. All of these in fact are isolated systems.

6. A single car slips on an icy road. (Friction

with the ice is negligible.) System: the car

7. Two cars slipping on an icy road collide

with one another. (Friction with the ice is

negligible.) System: the two cars

055 (part 1 of 3) 10.0 points

An air puck of mass 0.12 kg is tied to a string

and allowed to revolve in a circle of radius

1.4 m on a horizontal, frictionless table. The

other end of the string passes through a hole

in the center of the table and a mass of 0.43 kg

is tied to it. The suspended mass remains in

equilibrium while the puck revolves.

5.08 m

3.411 kg

4. A billiard ball collides with another billiard ball on a level pool table. (Ignore friction with the table during the instant of the collision.) System: the two balls

0.12 kg

1.4 m

6.822 kg

v

Calculate the height to which the block

with mass 3.411 kg rises after rebounding

from the collision.

Answer in units of m

0.43 kg

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

What is the tension in the string? The

acceleration due to gravity is 9.8 m/s2 .

Answer in units of N

056 (part 2 of 3) 10.0 points

What is the horizontal force acting on the

puck?

Answer in units of N

057 (part 3 of 3) 10.0 points

What is the speed of the puck?

Answer in units of m/s

058

Find the distance D where the mass comes

to rest. The acceleration due to gravity is

9.8 m/s2 .

Answer in units of m

059

v

A 6 kg mass slides to the right on a surface

having a coeﬃcient of friction 0.25 as shown

in the ﬁgure. The mass has a speed of 6 m/s

when contact is made with a spring that has

a spring constant 107 N/m. The mass comes

to rest after the spring has been compressed

a distance d. The mass is then forced toward

the left by the spring and continues to move

in that direction beyond the unstretched position. Finally the mass comes to rest a distance D to the left of the unstretched spring.

v

107 N/m

6 kg

At the position shown in the ﬁgure, which

arrow best represents the direction of the acceleration of the mass? The acceleration of gravity is 9.8 m/s2 and no external forces act

on the system.

1.

2.

6 m/s

3.

6 kg

4.

d

v⊃ = 0

5.

6 kg

6. The mass is traveling at a constant velocity, so it has no acceleration.

vf

6 kg

6 kg

7.

8.

D

10.0 points

A mass slides with negligible friction on a

circular track of 1 m radius oriented vertically.

Its speed at the position shown in the ﬁgure

is 3.13 m/s.

10.0 points

v⊢ = 0

15

107 N/m

9.

µ = 0.25

1

This print-out should have 59 questions.

Multiple-choice questions may continue on

the next column or page – ﬁnd all choices

before answering.

face of the table? Assume the boxes each

have masses of 2.0 kg, the coeﬃcient of static

friction is µs between table and box, and the

acceleration due to gravity is 10 m/s2 .

001 10.0 points

A block accelerates 3 m/s2 down a plane inclined at angle 27.0◦. The acceleration of gravity is 9.81 m/s2 .

1. The force of the static friction would have

a vertical component in this situation, and

that is impossible since it must be parallel to

the table surface.

2

3

s

m/

2. 20 N

3. Very small, almost zero

m

µk

27◦

4. 2.5 N

5. 5.0 N

Find µk between the block and the inclined

plane.

1. 0.166

6. fs would have to be greater than 20 N,

which is physically impossible, so this is not a

realistic situation.

7. 10 N

2. 0.148

8. Impossible to say from the information

given.

3. 0.510

003

4. 0.853

10.0 points

A block with an initial velocity v0 slides up

and back down a frictionless incline.

5. 1.289

002

10.0 points

Two identical boxes are connected by a

string of negligible mass, which runs across a

frictionless peg. One box is on a horizontal

table, while the other box hangs vertically.

If the hanging box is released from rest, it

remains at rest.

m

m

What must be the force of static friction

between the box on the table, and the sur-

v0

θ

Which graph best represents a description

of the velocity of the block versus time? The

initial position of the block is the origin;

i.e., x = 0 at t = 0 . Consider down the track

to be the positive x-direction.

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

v

v

t

1.

2

t

8.

v

v

t

2.

t

9.

v

t

3.

v

10.

t

v

t

4.

v

t

5.

004 10.0 points

If a car hits a tree, the car’s occupants (if

the car has no seat belts or air bags) will be

violently accelerated forward and strike the

dashboard with murderous force, due to an

initial forward force exerted on their bodies

by the backs of their seats.

1. False

2. None of these

v

t

6.

3. This may happen in a few cases, but it is

very rare.

4. True

5. This may happen in many cases, but not

in every case.

v

7.

t

005 (part 1 of 5) 10.0 points

A car travels at a speed of 30 m/s around a

curve of radius 69 m.

The acceleration of gravity is 9.8 m/s2 .

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

3

In this case, which of these two forces has

the smaller magnitude?

1. m g

1. 9

g

M

2. None of these

µ

36◦

3. Both have the same magnitude.

4. n

5. If a is downward, n = 0 .

What is the net centripetal force needed to

keep the car from skidding sideways?

Answer in units of N

006 (part 2 of 5) 10.0 points

Were there no friction between the car’s tires

and the road, what centripetal force could be

provided just by the banking of the road?

Answer in units of N

007 (part 3 of 5) 10.0 points

Now suppose the friction force is suﬃcient to

keep the car from skidding. Calculate the

magnitude of the normal force exerted on the

car by the road’s surface. Hint: Check the

correctness of your answer to the ﬁrst question

before proceeding with this and the following

questions.

Answer in units of N

008 (part 4 of 5) 10.0 points

Calculate the magnitude of the friction force.

Answer in units of N

009 (part 5 of 5) 10.0 points

Calculate the lowest possible value of the

static friction coeﬃcient µs that would prevent the car from skidding. 010 10.0 points

Consider a person standing in an elevator that

is moving at constant speed upward. The

person, of mass m, has two forces acting upon

him, the downward force m g due to gravity,

and the upward supporting force n exerted by

the ﬂoor of the elevator.

6. If a is downward, mg = 0 .

011 (part 1 of 3) 10.0 points

Consider a loop-the-loop system where the

radius of the loop is R. A small block (of

negligible size) is released from rest at the

1

point P , which is at a height of 4 R.

8

m

P

33

R

8

C

R

B

A

What is the kinetic energy KB at B? Friction between the block and the track is negligible. 19

mgR

5

18

2. KB =

mgR

5

31

mgR

3. KB =

8

25

4. KB =

mgR

8

1. KB =

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

5. KB =

16

mgR

5

2. NA =

6. KB =

11

mgR

5

3. NA =

7. KB =

26

mgR

7

4. NA =

8. KB =

19

mgR

7

5. NA =

9. KB =

17

mgR

7

6. NA =

10. KB =

19

mgR

8

7. NA =

012 (part 2 of 3) 10.0 points

What is the tangential speed vC at C?

8. NA =

9. NA =

37

mg

5

23

mg

2

27

mg

4

39

mg

4

35

mg

4

73

mg

7

45

mg

4

55

mg

7

37

mg

4

1. vC =

16

gR

5

2. vC =

34

gR

7

3. vC =

38

gR

7

4. vC =

12

gR

5

5. vC =

17

gR

4

1. Twice as far

6. vC =

8

gR

3

2. Half as far

7. vC =

23

gR

4

8. vC =

20

gR

7

10. NA =

014 10.0 points

Car B has the same mass as Car A but is

going twice as fast.

If the same constant force brings both cars

to a stop, how far will car B travel in coming

to rest as compared to the distance car A

traveled?

3. Eight times as far

4. Three times as far

5. None of these

9. vC =

27

gR

4

6. The same distance

10. vC =

11

gR

2

7. A quarter as far

013 (part 3 of 3) 10.0 points

What is the force NA with which the track

pushes up on the block at the point A (at the

bottom of the loop)?

21

1. NA =

mg

2

4

8. Insuﬃcient information is given.

9. Four times as far

015

10.0 points

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

A ball of mass M is suspended by a thin

string (of negligible mass) from the ceiling

of an elevator. The vertical motion of the

elevator as it travels up and down is described

in the statements below. Indicate for each of

the situations described the relation between

value of the tension T in the string and the

weight of the ball M g, or whether one cannot

tell.

T

v

M

Elevator

with a

weight

held by

a string

inside it

5

block is 9.78 kg and the acceleration of gravity

is 9.8 m/s2 .

Answer in units of m/s2

017 10.0 points

A balloon of mass M is ﬂoating motionless in

the air. A person of mass less than M is on

a rope ladder hanging from the balloon. The

person begins to climb the ladder at a uniform

speed v relative to the ground.

How does the balloon move relative to the

ground?

1. Up with a speed less than v

2. Down with speed v

3. Down with a speed less than v

The elevator is traveling upwards and its

upwards velocity is increasing as it starts towards a higher ﬂoor. 1. T < M g

2. T = M g

3. T > M g

4. Cannot be determined.

016 10.0 points

The block is released from rest on the incline

with the spring initially unstretched:

78.2 N/m

x

8

9. 7

5. Up with speed v

018 10.0 points

Two carts are put back-to-back on a track.

Cart A has a spring-loaded piston; cart B,

which has twice the inertial mass of cart A, is

entirely passive. When the piston is released,

it pushes against cart B, and the carts move

apart.

How do the magnitudes of the ﬁnal momenta p and kinetic energies K compare? 1. pA = pB , KA > KB

2. pA < pB , KA = KB

3. pA < pB , KA < KB

4. pA > pB , KA > KB

kg

µ=

4. The balloon does not move.

0

30◦

5. pA > pB , KA < KB

6. pA = pB , KA < KB

Choosing down the incline as the positive

direction, what is its acceleration at its lowest

point? The angle of inclination is 30 ◦ , the

spring constant is 78.2 N/m the mass of the

7. pA = pB , KA = KB

8. pA > pB , KA = KB

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

9. pA < pB , KA > KB

019 10.0 points

Two blocks of masses M and 3M are placed

on a horizontal, frictionless surface. A light

spring is attached to one of them, and the

blocks are pushed together with the spring

between them.

3M

M

Before

(a)

v

impact lifts the block 0.23 m up. (That is, the

block — with the bullet stuck in it — rises

0.23 m up above its initial position, and then

falls back down.)

Given g = 9.8 m/s2 . What was the initial

velocity of the bullet?

Answer in units of m/s

021 (part 1 of 2) 10.0 points

Consider the 693 N weight held by two cables

shown below. The left-hand cable had tension T2 and makes an angle of 54 ◦ with the ceiling. The right-hand cable had tension T1

and makes an angle of 50◦ with the ceiling.

3M

M

54 ◦

◦

50

The two blocks are at rest ﬁrst. Then the

cord holding them together is burned, after

which the block of mass 3M moves to the

right with a speed of 2 m/s. What is the

speed of the block of mass M?

1. 0 m/s

T1

T2

After

(b)

6

693 N

a) What is the tension in the cable labeled

T1 slanted at an angle of 50◦ ?

Answer in units of N

022 (part 2 of 2) 10.0 points

a) What is the tension in the cable labeled T2

slanted at an angle of 54◦ ?

Answer in units of N

2. 6 m/s

3. 2 m/s

4. impossible to determine

5. 1.5 m/s

6. 0.67 m/s

7. 4 m/s

020 10.0 points

A 11.7 g bullet is ﬁred vertically into a 1.65 kg

block of wood.

023 10.0 points

You are given two carts, A and B. They look

identical and you are told that they are made

of the same material. You place A at rest on

an air track and give B a constant velocity directed to the right so that it collides elastically with A. After the collision, both carts move

to the right, the velocity of B being smaller

than what it was before the collision.

What do you conclude?

1. Cart A is hollow.

v0

The bullet gets stuck in the block, and the

2. need more information

3. Cart B is hollow.

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

4. The two carts are identical.

1. 0.2

024 10.0 points

You are on a rooftop and you throw one ball

straight down and another straight up. The

second ball, after rising, falls and also strikes

the ground below.

If air resistance can be neglected and if your

downward and upward initial speeds are the

same, how will the speed of the balls compare

upon striking the ground?

1. They have same speed.

2. The speed of the second ball is smaller

than that of the ﬁrst one.

3. The speed of the second ball is larger than

that of the ﬁrst one.

2. 0.05

3. 20

4. 2

5. 0.5

027 10.0 points

On the surface of the earth is a pendulum of

mass m and length ℓ.

If the pendulum is allowed to swing down

from rest starting from an initial horizontal

position, with the forces acting being T, the

tension in the string, and m g , the force of

gravity, how much work has been done on the

pendulum as it swings through the vertical

position?

4. More information is needed

1. m g +T times

025 10.0 points

A block starts at rest and slides down a frictionless track except for a small rough area on a horizontal section of the track (as shown in

the ﬁgure below).

It leaves the track horizontally, ﬂies through

the air, and subsequently strikes the ground.

The acceleration of gravity is 9.81 m/s2 .

9.81 m/s2

2.2 m

h

v

1.2 m

µ=0.2

4.15 m

At what height h above the ground is the

block released?

Answer in units of m

026 10.0 points

A horizontal force of 100 N is used to pull a

crate, which weighs 500 N, at constant velocity across a horizontal ﬂoor. What is the coeﬃcient of kinetic friction?

π

ℓ, the distance traveled.

2

2. T ℓ

3. m g ℓ, with the pendulum’s KE increasing

by this amount.

4. Zero; energy is conserved.

028

512 g

7

10.0 points

A 7 kg mass slides to the right on a surface

having a coeﬃcient of friction 0.15 as shown.

The mass has a speed of 4 m/s when contact is

made with a spring that has a spring constant

101 N/m. The mass comes to rest after the

spring has been compressed a distance d. The

mass is then forced toward the left by the

spring and continues to move in that direction

beyond the unstretched position. Finally the

mass comes to rest a distance D to the left of

the unstretched spring.

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

v

101 N/m

7 kg

4 m/s

7 kg

d

v⊃ = 0

8

How long does it take Tperiod for the ball to

rotate once around the axis?

Answer in units of s

031 10.0 points

A block is at rest on the incline shown in the

ﬁgure. The coeﬃcients of static and kinetic

friction are µs = 0.6 and µk = 0.51, respectively.

The acceleration of gravity is 9.8 m/s2 .

7 kg

43

vf

kg

µ

28◦

7 kg

v⊢ = 0

7 kg

101 N/m

D

µ = 0.15

Find the compressed distance d. The acceleration of gravity is 9.8 m/s2 . Answer in units of m

029 (part 1 of 2) 10.0 points

A small metal ball is suspended from the ceiling by a thread of negligible mass. The ball is then set in motion in a horizontal circle so

that the thread describes a cone.

The acceleration of gravity is 9.8 m/s2 .

What is the frictional force acting on the

43 kg mass?

Answer in units of N

032 10.0 points

Two crates are touching, resting on a practically frictionless surface. If you apply a force F with your hand against the larger crate

of mass M , both crates accelerate across the

surface, and remain in contact.

a

F′

F

M

m

Which statement is wrong?

◦

20

9.8 m/s2

1. The force F ′ = −m a.

1. 8

m

v

5.1 kg

What is the speed of the ball when it is in

circular motion?

Answer in units of m/s

030 (part 2 of 2) 10.0 points

2. The smaller crate exerts a force F ′ backward on the larger crate, equal and opposite to the force (not shown) that the larger crate

exerts forward on the smaller one to accelerate it.

3. The forces F and F ′ are equal and opposite, as required by Newton’s third law. 4. The magnitude of the acceleration of the

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

F

, where F

M +m

is the magnitude of F and m is the mass of

the smaller crate.

two crates will be given by

033 10.0 points

Five ramps lead from the ground to the second

ﬂoor of a workshop, as sketched below. All

ﬁve ramps have the same height; ramps B,

C, D and E have the same length; ramp A is

longer than the other four. You need to push

a heavy cart up to the second ﬂoor and you

may choose any one of the ﬁve ramps.

9

034 10.0 points

A box is attached to an unstretched spring

of force constant k and rests on a horizontal

tabletop. The box is moved out to the right

a distance ℓ along the table, stretching the

spring, and released. It remains at rest when

released.

k

m

ℓ

A

B

C

What is the force of static friction in this

situation?

1. fs = µs m g to the right.

2. fs = k ℓ to the right.

D

3. fs = k ℓ to the left.

E

Assuming no frictional forces on the cart,

which ramp would require you to do the least

work?

1. Unable to determine without knowing the

exact proﬁles of ramps C, D or E.

2. Ramp D.

3. Same work for all ﬁve ramps.

4. Ramp B.

5. Ramp A.

6. Same work for the straight ramps A and

B; less work for ramps C, D, and E.

7. Same work for ramps B, C, D or E; more

work for ramp A.

8. Ramp C.

9. Ramp E.

4. fs = µs m g to the left.

035 10.0 points

A bowling ball is hanging in mid-air at rest

in a room on board the International Space

Station. An astronaut throws a golf ball directly at the bowling ball, and they collide elastically.

Compared to its values before the collision,

the golf ball after the collision has a

1. All of these

2. momentum that has changed from p to

roughly −p .

3. slightly less momentum.

4. slightly less kinetic energy.

5. None of these

036 10.0 points

Static friction 0.49 between a 0.9 kg block

and a 3.9 kg cart. There is no kinetic friction

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

F

3.9 kg

µ = 0.49

9.8 m/s2

between the cart and the horizontal surface.

The acceleration of gravity is 9.8 m/s2 .

10

3.27 m

0.9 kg

What minimum force F must be exerted on

the 3.9 kg cart in order for the 0.9 kg block

not to fall?

What minimum coeﬃcient of friction between a rider’s clothing and the wall of the cylinder is needed to keep the rider from

slipping? The acceleration due to gravity

is 9.81 m/s2 .

1. F = 91 N

2. F = 76 N

3. F = 94 N

038 10.0 points

A 4.2 kg block is pushed along the ceiling with

a constant applied force of 80 N that acts at

an angle of 56◦ with the horizontal. The block

2

accelerates to the right at 5.4 m/s2 .

4. F = 77 N

µ

5. F = 96 N

4.2 kg

6. F = 49 N

5.4 m/s2

80

7. F = 66 N

N

◦

56

8. F = 70 N

9. F = 68 N

10. F = 74 N

037 10.0 points

In a popular amusement-park ride, a cylinder of radius 3.27 m is set in rotation at an angular speed of 5.36 rad/s, as shown in the

ﬁgure. The ﬂoor then drops away, leaving the

riders suspended against the wall in a vertical

position.

What is the coeﬃcient of kinetic friction

between the block and the ceiling? The acceleration due to gravity is 9.81 m/s2 . 039

10.0 points

A box of mass M is being accelerated up a

vertical wall by a constant force F applied at

an angle θ with the vertical, as shown.

a

M

F

θ

µk

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

If the coeﬃcient of kinetic friction between

the box and wall is µk , what is the magnitude

of the acceleration of the box?

F

from Newton’s Second Law

M

F

(cos θ − µk sin θ) − g

2. a =

M

F sin θ

3. a =

M

1. a =

4. a = µk g

F

(sin θ − µk cos θ) + g

M

F

(cos θ + µk sin θ) − g

6. a =

M

F sin θ

7. a = g −

M

F

8. a =

−g

M

F

(sin θ − µk cos θ) − g

9. a =

M

11

Find the speed of the bullet. The acceleration due to gravity is 9.81 m/s2 . Answer in units of m/s

041 10.0 points

A pendulum made of a string and a sphere

is able to swing in a vertical plane. The

pendulum is released from a position of 70 ◦

from vertical as shown in the ﬁgure below.

The string hits a peg located a distance d

below the point of suspension and rotates

about the peg.

The acceleration of gravity is 9.8 m/s2 .

5. a =

10. a = 0 since kinetic friction makes the box

slide at constant velocity

040

◦

33

2.8 m

vi

5.2 kg

d

70 ◦

9.8 m/s2

Find the smallest value of d (highest peg

position) in order for the sphere to swing in a

full circle centered on the peg.

Answer in units of m

10.0 points

A bullet of mass 3 g is ﬁred into the bob of

a ballistic pendulum of mass 5.2 kg. When

the bob is at its maximum height, the strings

make an angle of 33 ◦ with the vertical. The

length of the pendulum is 2.8 m.

3g

m

7 kg 10

vf

042 10.0 points

Note: The pendulum bob is released at a

height below the height of the peg.

A pendulum made of a string of length

10.5 m and a spherical bob of mass 7.3 kg

and negligible raius swings in a vertical plane.

The pendulum is released from an angular

position 39 ◦ from vertical as shown in the

ﬁgure below. The string hits a peg located

a distance 6 m below the point of suspension

and swings about the peg up to an angle α

on the other side of the peg. Then, the bob

proceeds to oscillate back and forth between

these two angular positions.

The acceleration of gravity is 9.8 m/s2 .

7.3 kg

39 ◦

α

9.8 m/s2

What is the maximum angle α which the

pendulum will swing to the right after hitting

the peg as shown above?

Answer in units of ◦

043 10.0 points

Consider the acceleration of block with

mass m across the frictionless table towards

the pulley.

Case I

m

In case I a block of mass m is attached to

the end of the string.

m

Case II

vx

1.3 m

µ=0.3

∆x

What is the speed v of the block when it

leaves the track?

Answer in units of m/s

045 (part 2 of 3) 10.0 points

What is the horizontal distance x the block

travels in the air?

Answer in units of m

046 (part 3 of 3) 10.0 points

What is the total speed of the block when it

hits the ground?

Answer in units of m/s

mg

In case II a force of m g is acts on the end

of the string.

The acceleration of block m is

1. greater in case I.

8.1 kN/m 501 g

5.3 cm

m

12

044 (part 1 of 3) 10.0 points

A block is pushed against the spring with

spring constant 8.1 kN/m (located on the lefthand side of the track) and compresses the spring a distance 5.3 cm from its equilibrium

position (as shown in the ﬁgure below).

The block starts at rest, is accelerated by

the compressed spring, and slides across a

frictionless track except for a small rough area

on a horizontal section of the track (as shown

in the ﬁgure below).

It leaves the track horizontally, ﬂies through

the air, and subsequently strikes the ground.

The acceleration of gravity is 9.8 m/s2 .

2.3 m

10

.5

m

6m

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

047 (part 1 of 2) 10.0 points

A wooden block hangs on a string. A bullet

hits and sticks in the block.

What is conserved in the collision of the

bullet with the block?

1. neither momentum nor mechanical energy

2. greater in case II.

2. momentum and mechanical energy

3. the same in both cases.

3. only mechanical energy

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

13

A

4. only momentum

048 (part 2 of 2) 10.0 points

After the bullet collides and sticks in the

wooden block that hangs on a string, the

block swings out from its lowest position and

reaches its highest position.

What is conserved in the motion after the

bullet has collided with the block and the

block swings up to the highest position?

1. momentum and mechanical energy

2. neither momentum nor mechanical energy

3. only momentum

4. only mechanical energy

049 (part 1 of 2) 10.0 points

Consider the 40 N weight held by two cables

shown below. The left-hand cable is horizontal.

◦

43

40 N

a) What is the tension in the cable slanted

at an angle of 43◦ ?

Answer in units of N

050 (part 2 of 2) 10.0 points

b) What is the tension in the horizontal cable?

Answer in units of N

051 10.0 points

Consider a frictionless roller coaster such as

depicted.

C

hA

16 m

B

Passenger cars start at point A with zero

initial speed, accelerate as they go down to

point B, swing around the circular vertical

loop B → C → B of radius 16 m, then go

on towards further adventures (not shown).

When a car goes through the top of the loop

(point C), the passengers feel weightless (for

just a moment).

What is the height hA of the starting

point A above the loop’s bottom B? The acceleration of gravity is 9.8 m/s2 . Answer in units of m

052 10.0 points

Consider a loop-the-loop system where the

radius of the loop is R. A small block (of

negligible size) is released from rest at the

4

point P , which is at a height of 4 R.

5

m

P

24

R

5

C

R

B

A

What is the force NA with which the track

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

pushes up on the block at the point A (at

the bottom of the loop)? Consider friction

between the block and the track to be negligible.

1. NA =

2. NA =

3. NA =

4. NA =

5. NA =

53

mg

5

65

mg

7

47

mg

5

21

mg

4

33

mg

4

14

054 10.0 points

Which of these systems is NOT an “isolated

system” to which conservation of momentum

can be applied?

1. A ball falls freely toward the ﬂoor. (Ignore

air friction.) System: the ball

2. Two masses connected by a spring oscillate on a frictionless tabletop. System: the two masses and the spring

3. A ball falls freely toward the ground.

(Ignore air friction.) System: the ball and the

earth

6. NA = 12 m g

7. NA =

8. NA =

9. NA =

10. NA =

31

mg

3

49

mg

5

35

mg

4

41

mg

5

053 10.0 points

Consider a frictionless track as shown in the

ﬁgure.

A block of mass 3.411 kg is released on

the track at a height 5.08 m above the level

surface. It slides down the track and makes a

head-on elastic collision with a block of mass

6.822 kg, initially at rest.

The acceleration of gravity is 9.8 m/s2 .

5. All of these in fact are isolated systems.

6. A single car slips on an icy road. (Friction

with the ice is negligible.) System: the car

7. Two cars slipping on an icy road collide

with one another. (Friction with the ice is

negligible.) System: the two cars

055 (part 1 of 3) 10.0 points

An air puck of mass 0.12 kg is tied to a string

and allowed to revolve in a circle of radius

1.4 m on a horizontal, frictionless table. The

other end of the string passes through a hole

in the center of the table and a mass of 0.43 kg

is tied to it. The suspended mass remains in

equilibrium while the puck revolves.

5.08 m

3.411 kg

4. A billiard ball collides with another billiard ball on a level pool table. (Ignore friction with the table during the instant of the collision.) System: the two balls

0.12 kg

1.4 m

6.822 kg

v

Calculate the height to which the block

with mass 3.411 kg rises after rebounding

from the collision.

Answer in units of m

0.43 kg

wong (eyw89) – Quiz 2 Practice – sudarshan – (57415)

What is the tension in the string? The

acceleration due to gravity is 9.8 m/s2 .

Answer in units of N

056 (part 2 of 3) 10.0 points

What is the horizontal force acting on the

puck?

Answer in units of N

057 (part 3 of 3) 10.0 points

What is the speed of the puck?

Answer in units of m/s

058

Find the distance D where the mass comes

to rest. The acceleration due to gravity is

9.8 m/s2 .

Answer in units of m

059

v

A 6 kg mass slides to the right on a surface

having a coeﬃcient of friction 0.25 as shown

in the ﬁgure. The mass has a speed of 6 m/s

when contact is made with a spring that has

a spring constant 107 N/m. The mass comes

to rest after the spring has been compressed

a distance d. The mass is then forced toward

the left by the spring and continues to move

in that direction beyond the unstretched position. Finally the mass comes to rest a distance D to the left of the unstretched spring.

v

107 N/m

6 kg

At the position shown in the ﬁgure, which

arrow best represents the direction of the acceleration of the mass? The acceleration of gravity is 9.8 m/s2 and no external forces act

on the system.

1.

2.

6 m/s

3.

6 kg

4.

d

v⊃ = 0

5.

6 kg

6. The mass is traveling at a constant velocity, so it has no acceleration.

vf

6 kg

6 kg

7.

8.

D

10.0 points

A mass slides with negligible friction on a

circular track of 1 m radius oriented vertically.

Its speed at the position shown in the ﬁgure

is 3.13 m/s.

10.0 points

v⊢ = 0

15

107 N/m

9.

µ = 0.25