Summer 2006

Answers are at the end

1. A car starts from rest and accelerates at a rate of 5 m/s2. How long does it take the car to go 30 m?

(a) 6 s (b) 90 s(c) 150 s(d) 0.17 s(e) 3.5 s

2. If I throw a ball straight up with an initial speed of 25 m/s, how high will it rise?

(a) 25 m(b) 2.6m(c) 32m(d) 20m(e) 13m

3. I throw a ball off a cliff 40 meters high. If the ball is thrown horizontally at a speed of 12 m/s, how far will it go before hitting the ground below?

?

(a) 48m(b) 39m(c) 7.3m(d) 24m(e) 34m

4. If I throw a rock straight up in the air, and ignore air resistance, then at the top of its arc it will have an acceleration (in m/s2) of

(a) 0.0 (b) 9.8, downward(c) 9.8, upward

(d) a value between 0 and 9.8, downward(e) between 0 and 9.8, upward

5. I walk from point A to point B in two stages, first going 22 meters east, and then 12 meters north. In order to go from A to B in a single stage, I should head in a direction θ, where θ is

N B

θ 12 m

A E

22 m

(a) 33o(b) 57o(c) 29o(d) 61o(e) 45o

6. A truck breaks down on the highway. A compact car comes along and offers to push the truck to the service station. As the car pushes the truck at a slow and constant speed, what can you say about the relative magnitudes of the forces exerted by the truck and car on one another?

(a) The truck exerts a greater force on the car than the car exerts on the truck.

(b) The car exerts a greater force on the truck than the truck exerts on the car.

(c) Neither the truck nor the car exerts a force on the other, since they are traveling at a constant speed.

(d) The force exerted by the car on the truck is equal to the force exerted by the truck on the car.

(e) The car exerts a force on the truck, but the truck does not exert a force on the car.

7. A given force F accelerates a given mass m at a rate of 2 m/s2. The same force will accelerate a mass of half the magnitude (m/2) at a rate of

(a) 1 m/s2 (b) 2 m/s2 (c) 4 m/s2 (d) 0.5 m/s2 (e) 8 m/s2

8. A car of mass 1000 kg rounds an unbanked curve of radius 80 m. If the coefficient of static friction between the tires and the road is 0.6, what is the maximum speed the car can go without slipping?

(a) 9.8 m/s (b) 21.7 m/s (c) 470 m/s (d) 32.5 m/s (e) 15.1 m/s 9. Two boxes, of mass 8 kg and 5 kg, respectively, are connected by a string. The 5 kg box is pulled to the right by a second string with a tension force of T = 40N. What is the tension in the connecting string?

?40N

8kg 5kg

(a) 15N(b) 40N(c) 25N(d) 20N(e) 8N

10. Mass m1 exerts a gravitational force F on mass m2 when they are 3 meters apart. When they are only 9 meters apart, what force does m1 exert on m2?

(a) 3F (b) 9F(c) 4F(d) F/3(e) F/9

11. A block of mass 3 kg, sliding at 8 m/s, hits a rough area of length 1.5 meters, which has a coefficient of kinetic friction of 0.3. What will be the block’s speed after passing over this rough area?

(a) 0.0 m/s (b) 4.6 m/s (c) 5.6 m/s (d) 7.4 m/s (e) 2.7 m/s

12. If a car going 30 mph can stop in 100 feet, how much distance does the same car require if stopping from a speed of 90 mph?

(a) 100 feet(b) 200 feet(c) 300 feet(d) 600 feet(e) 900 feet

13. A boy pulls a 20 kg box across the floor using a rope that makes an angle of 40o with the horizontal. If the tension in the rope is 50N, how much work is done by the tension force as the box is moved 30 m across the floor?

(a) 1500 J(b) 5880 J(c) 964 J(d) 1149 J(e) 4504 J

14. Kinetic energy is conserved in

(a) all collisions

(b) only elastic collisions

(c) only inelastic collisions

(d) only collisions between equal mass objects

(e) outer space only

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