1
A wooden block of mass 0.60 kg is on a rough horizontal surface. A force of 12 N is applied to the block and it accelerates at 4.0 m s –2.
4.0 m s–2 wooden block
12 N
What is the magnitude of the frictional force acting on the block?
A
B
9.6 N
C
14 N
D
2
2.4 N
16 N
A submarine descends vertically at constant velocity. The three forces acting on the submarine are viscous drag, upthrust and weight.
Which relationship between their magnitudes is correct?
A
B
weight = drag
C
weight < upthrust
D
weight > upthrust
A ruler of length 0.30 m is pivoted at its centre. Equal and opposite forces of magnitude 2.0 N are applied to the ends of the ruler, creating a couple as shown.
2.0 N
50°
ruler
pivot
50°
2.0 N
What is the magnitude of the torque of the couple on the ruler when it is in the position shown?
A
0.23 Nm
B
0.39 Nm
C
0.46 Nm
D
0.60 Nm
Compiled nd rearrnged by Sjit Chandra Shakya
3
weight < drag
2
4
A ball falls from rest through air and eventually reaches a constant velocity.
For this fall, forces X and Y vary with time as shown.
force Y
force X
0
0
0
time
0
time
What are forces X and Y ? force X
A
air resistance
resultant force
B
air resistance
weight
C
upthrust
resultant force
D
upthrust
weight
The diagram shows four forces applied to a circular object.
30 N
20 N
20 N
30 N
Which of the following describes the resultant force and resultant torque on the object? resultant force
resultant torque
A
zero
zero
B
zero
non-zero
C
non-zero
zero
D
non-zero
non-zero
Compiled nd rearrnged by Sjit Chandra Shakya
5
force Y
3
6
A balloon is acted upon by three forces, weight, upthrust and sideways force due to the wind, as shown in the diagram. upthrust 10 000 N
sideways force
500 N
weight
9000 N
What is the vertical component of the resultant force on the balloon?
A
7
500 N
B
1000 N
C
10 000 N
D
10 500 N
The vector diagram shows three coplanar forces acting on an object at P.
3N
P
4N
4N
The magnitude of the resultant of these three forces is 1 N.
What is the direction of this resultant?
8
↓
B
↓
C
↓
What is meant by the weight of an object?
A
the gravitational field acting on the object
B
the gravitational force acting on the object
C
the mass of the object multiplied by gravity
D
the object’s mass multiplied by its acceleration
D
↑
Compiled nd rearrnged by Sjit Chandra Shakya
A
4
9
A uniform beam of weight 50 N is 3.0 m long and is supported on a pivot situated 1.0 m from one end. When a load of weight W is hung from that end, the beam is in equilibrium, as shown in the diagram. 3.0 m
1.0 m
W
pivot
What is the value of W ?
A
25 N
B
50 N
C
75 N
D
100 N
10 The diagram shows a sign of weight 20 N suspended from a pole, attached to a wall. The pole is kept in equilibrium by a wire attached at point X of the pole.
wire wall pole
X
SIGN
The force exerted by the pole at point X is F, and the tension in the wire is 40 N.
Which diagram represents the three forces acting at point X?
A
B
F
20 N
40 N
40 N
20 N
C
D
40 N
20 N
F
F
20 N
40 N
Compiled nd rearrnged by Sjit Chandra Shakya
F
5
11 An L-shaped rigid lever arm is pivoted at point P.
P
5N
2m
2m
10 N
1m
3m
20 N
Three forces act on the lever arm, as shown in the diagram.
What is the magnitude of the resultant moment of these forces about point P?
A
30 N m
B
C
35 N m
50 N m
D
90 N m
12 The vector diagram shows three coplanar forces acting on an object at P.
3N
P
4N
4N
The magnitude of the resultant of these three forces is 1 N.
What is the direction of this resultant?
B
C
13 A cyclist is riding at a steady speed on a level road.
D
Compiled nd rearrnged by Sjit Chandra Shakya
A
According to Newton’s third law of motion, what is equal and opposite to the backward push of the back wheel on the road?
A
the force exerted by the cyclist on the pedals
B
the forward push of the road on the back wheel
C
the tension in the cycle chain
D
the total air resistance and friction force
6
14 The diagrams show three forces acting on a body.
In which diagram is the body in equilibrium?
A
B
C
D
15 Two rigid rods, XZ and YZ, are fixed to a vertical wall at points X and Y.
A load of weight W is hung from point Z.
The load is not moving.
Z
X
W
load
Y
Which diagram shows the forces acting at point Z?
A
B
W
force in YZ
force in XZ
W
C
D
force in XZ
W
force in YZ
force in YZ
force in XZ
W
force in YZ
Compiled nd rearrnged by Sjit Chandra Shakya
force in XZ
7
16 A force F is applied to a beam at a distance d from a pivot. The force acts at an angle θ to a line perpendicular to the beam.
F
θ
pivot
d
Which combination will cause the largest turning effect about the pivot?
F
d
θ
A
large
large
large
B
large
large
small
C
small
small
large
D
small
large
small
17 A rigid uniform bar of length 2.4 m is pivoted horizontally at its mid-point.
0.8 m
0.8 m
200 N
300 N
Weights are hung from two points of the bar as shown in the diagram. To maintain horizontal equilibrium, a couple is applied to the bar.
What is the torque and direction of this couple?
40 N m clockwise
B
40 N m anticlockwise
C
80 N m clockwise
D
80 N m anticlockwise
18 Which of the following pairs of forces, acting on a circular object, constitutes a couple?
B
A
F
C
D
2F
F
F
F
2F
F
F
Compiled nd rearrnged by Sjit Chandra Shakya
A
8
19 An object has an initial velocity u. It is subjected to a constant force F for t seconds, causing a constant acceleration a. The force is not in the same direction as the initial velocity.
A vector diagram is drawn to find the final velocity v. u X v What is the length of side X of the vector diagram?
A
F
B
Ft
at
C
D
u + at
20 Two 8.0 N forces act at each end of a beam of length 0.60 m. The forces are parallel and act in opposite directions. The angle between the forces and the beam is 60 °.
8.0 N
60°
0.60 m
60°
8.0 N
What is the torque of the couple exerted on the beam?
A
2.4 N m
B
4.2 N m
C
4.8 N m
D
9.6 N m
21 A submarine is in equilibrium in a fully submerged position.
steel
sea water What causes the upthrust on the submarine?
A
The air in the submarine is less dense than sea water.
B
The sea water exerts a greater upward force on the submarine than the weight of the steel.
C
The submarine displaces its own volume of sea water.
D
There is a difference in water pressure acting on the top and bottom of the submarine.
Compiled nd rearrnged by Sjit Chandra Shakya
air
9
22 A uniform ladder rests against a vertical wall where there is negligible friction. The bottom of the ladder rests on rough ground where there is friction. The top of the ladder is at a height h above the ground and the foot of the ladder is at a distance 2a from the wall.
The diagram shows the forces which act on the ladder.
F ladder h
W
W
a
F a Which equation is formed by taking moments?
A
Wa + Fh
= 2W a
B
Fa + Wa
= Fh
C
W a + 2W a = F h
D
W a – 2W a = 2F h
23 A spanner is used to tighten a nut as shown.
0.04 m
0.25 m
F = 200 N
What is the resistive torque, in an anticlockwise direction, preventing further tightening?
A
8Nm
B
25 N m
C
50 N m
D
800 N m
Compiled nd rearrnged by Sjit Chandra Shakya
A force F is applied at right-angles to the spanner at a distance of 0.25 m from the centre of the nut. When the nut is fully tightened, the applied force is 200 N.
10
24 A uniform metre rule of mass 100 g is supported by a knife-edge at the 40 cm mark and a string at the 100 cm mark. The string passes round a frictionless pulley and carries a mass of 20 g as shown in the diagram.
0
40
20
60
80
100
20 g
At which mark on the rule must a 50 g mass be suspended so that the rule balances?
A
4 cm
B
36 cm
C
44 cm
D
96 cm
25 A car of mass 750 kg has a horizontal driving force of 2.0 kN acting on it. It has a forward horizontal acceleration of 2.0 m s–2.
resistive force driving force
What is the resistive force acting horizontally?
A
0.5 kN
B
1.5 kN
C
2.0 kN
D
3.5 kN
What is the order of increasing magnitude of these three forces?
A
upthrust → viscous drag → weight
B
viscous drag → upthrust → weight
C
viscous drag → weight → upthrust
D
weight → upthrust → viscous drag
Compiled nd rearrnged by Sjit Chandra Shakya
26 A ball is falling at terminal speed in still air. The forces acting on the ball are upthrust, viscous drag and weight.
11
27 A hinged door is held closed in the horizontal position by a cable.
Three forces act on the door: the weight W of the door, the tension T in the cable, and the force H at the hinge.
cable
wall
T door hinge
H
W
Which list gives the three forces in increasing order of magnitude?
A
H,T,W
B
T,H,W
C
W,H,T
D
W,T,H
28 Two parallel forces, each of magnitude F, act on a body as shown.
F
d
F
What is the magnitude of the torque on the body produced by these forces?
A
Fd
B
Fs
C
2Fd
D
2Fs
Compiled nd rearrnged by Sjit Chandra Shakya
s
12
29 The diagram shows four forces applied to a circular object.
45 N
30 N
30 N
45 N
Which of the following describes the resultant force and resultant torque on the object? resultant force
resultant torque
A
non-zero
non-zero
B
non-zero
zero
C
zero
non-zero
D
zero
zero
30 The diagrams represent systems of coplanar forces acting at a point. The lengths of the force vectors represent the magnitudes of the forces.
Which system of forces is in equilibrium?
A
B
C
D
0.5 m
2.5 m
beam
pivot
300 N
What is the weight of the beam?
A
300 N
B
480 N
C
600 N
D
960 N
Compiled nd rearrnged by Sjit Chandra Shakya
31 A long uniform beam is pivoted at one end. A force of 300 N is applied to hold the beam horizontally. 13
32 Which two vector diagrams represent forces in equilibrium?
P
R
A
Q and R
C
R and S
D
S
P and Q
B
Q
S and P
33 What is meant by the weight of an object?
A
the gravitational field acting on the object
B
the gravitational force acting on the object
C
the mass of the object multiplied by gravity
D
the object’s mass multiplied by its acceleration
34 A uniform beam of weight 100 N is pivoted at P as shown. Weights of 10 N and 20 N are attached to its ends.
The length of the beam is marked off at 0.1 m intervals.
At which point should a further weight of 20 N be attached to achieve equilibrium?
0.1 m
A
B
C
D
P
10 N
20 N
Compiled nd rearrnged by Sjit Chandra Shakya
0.4 m
0.6 m
14
35 The diagram shows a cannon ball fired from a cannon. cannon cannon ball The mass of the cannon is 1000 kg and the mass of the cannon ball is 10 kg.
The recoil velocity of the cannon is 5 m s–1 horizontally.
What is the horizontal velocity of the cannon ball?
A
B
200 m s–1
500 m s–1
C
2000 m s–1
D
5000 m s–1
36 A block of mass 0.60 kg is on a rough horizontal surface. A force of 12 N is applied to the block and it accelerates at 4.0 m s –2.
4.0 m s–2 block 12 N
What is the magnitude of the frictional force acting on the block?
A
B
2.4N
5.3 N
C
D
6.7 N
9.6 N
38 A wooden block rests on a rough board. The end of the board is then raised until the block slides down the plane of the board at constant velocity v. block v
Which row describes the forces acting on the block when sliding with constant velocity? frictional force on block
resultant force on block
A
down the plane
down the plane
B
down the plane
zero
C
up the plane
down the plane
D
up the plane
zero
Compiled nd rearrnged by Sjit Chandra Shakya
board
15
39 Three coplanar forces, each of magnitude 10 N, act through the same point of a body in the directions shown.
10 N
10 N
30o 30o
10 N
What is the magnitude of the resultant force?
A
B
0N
C
1.3 N
D
7.3 N
10 N
40 Which force is caused by a pressure difference?
A
friction
B
upthrust
C
viscous force
D
weight
41 A car with front-wheel drive accelerates in the direction shown.
A
B
C
D
Compiled nd rearrnged by Sjit Chandra Shakya
Which diagram best shows the direction of the total force exerted by the road on the front wheels? 16
42 A rigid circular disc of radius r has its centre at X. A number of forces of equal magnitude F act at the edge of the disc. All the forces are in the plane of the disc.
Which arrangement of forces provides a moment of magnitude 2Fr about X?
A
B
F
X
X
F
F
C
D
F
X
X
F
F
F
F
43 The diagram shows a plan view of a door which requires a moment of 12 N m to open it. door wall
wall
0.80 m
hinge
What is the minimum force that must be applied at the door’s midpoint to ensure it opens?
B
4.8 N
C
9.6 N
D
15 N
30 N
44 Which pair of forces acts as a couple on the circular object?
A
C
B
F
F
D
2F
F
F
2F
F
F
Compiled nd rearrnged by Sjit Chandra Shakya
A
17
45 Which two vector diagrams represent forces in equilibrium?
R
A
P and Q
B
Q
S
Q and R
C
R and S
D
S and P
Compiled nd rearrnged by Sjit Chandra Shakya
P
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