Self-Test: Momentum in 1D and 2D Test #1
Suggested Time: 60 minutes

1. Which of the following best represents the momentum of a small car travelling at a city speed limit
 A. 1,000 kg × m/s B. 10,000 kg × m/s C. 100,000 kg × m/s D. 1,000,000 kg × m/s

2. A 0.080 kg tennis ball travelling east at 15 m/s is struck by a tennis racquet, giving it a velocity of 25 m/s, west. What are the magnitude and direction of the impulse given to the ball?
 MAGNITUDE DIRECTION A. 0.80 N s Eastward B. 0.80 N s Westward C. 3.2 N s Eastward D. 3.2 N s Westward

3. Which of the following describes kinetic energy and momentum before and after a perfectly elastic collision?
 KINETIC ENERGY MOMENTUM A. Not Conserved Not Conserved B. Not Conserved Conserved C. Conserved Not Conserved D. Conserved Conserved

4. The 2.0 kg head of an axe strikes a tree horizontally at 40 m/s. The blade penetrates 0.040 m into the tree. What is the average force exerted by the blade on this tree?
 A. 2.0 × 101 N B. 2.0 × 103 N C. 2.0 × 104 N D. 4.0 × 104 N

5. A 900 kg car travelling at 12 m/s due east collides with a 600 kg car travelling at 24 m/s due north. As a result of the collision, the two cars lock together and move in what final direction?
 A. 45° N of E B. 53° N of E C. 63° N of E D. 69° N of E

6. Which of the following are equivalent units for change in momentum?
 A. kg × m/s2 B. N s C. kg × s/m D. N/s

7. A 1.2 kg ball moving due east at 40 m/s strikes a stationary 6.0 kg object. The 1.2 kg ball rebounds to the west at 25 m/s. What is the speed of the 6.0 kg object after the collision?
 A. 3.0 m/s B. 13 m/s. C. 15 m/s D.65 m/s

8. A 0.30 kg ball rolls off a horizontal surface as shown in the diagram. What is the magnitude of the impulse given to the ball by gravity during the 0.90 s it takes the ball to fall to the ground? A. 1.5 N s B. 2.6 N s C. 3.0 N s D. 4.1 N s

9. A ball is thrown at 15 m/s towards various barriers. In which case does the ball experience the greatest impulse?

A. The ball hits a wall and rebounds at 2.0 m/s.

B. The ball hits a wall and rebounds at 7.0 m/s.

C. The ball hits a wall, sticks to it and stops moving.

D. The ball breaks a window and continues moving at 10 m/s in the same direction.

10. A small explosive device sliding to the right breaks into two pieces. The momentum of fragment 1 after the explosion is 23 kg × m/s. What is the momentum of fragment 2 after the explosion?

 A. 22 kg × m/s B. 23 kg × m/s C. 30 kg × m/s D. 32 kg × m/s

11. Which set of conditions is true in all inelastic collisions?
 MOMENTUM KINETIC ENERGY TOTAL ENERGY A. Conserved Conserved Conserved B. Conserved Not conserved Conserved C. Not conserved Not conserved Conserved D. Not conserved Conserved Not conserved

12. The diagram shows a collision between a 4.0 kg toy car and a stationary 8.0 kg toy truck. After the collision, the car bounces back at 1.0 m/s while the truck goes forward at 2.0 m/s. Based on these values, are momentum and kinetic energy conserved? MOMENTUM KINETIC ENERGY A. Conserved Conserved B. Conserved Not Conserved C. Not Conserved Conserved D. Not Conserved Not Conserved

13. A 0.15 kg ball moving at 40 m/s is struck by a bat. The bat reverses the ball's direction and gives it a speed of 50 m/s. What average force does the bat apply to the ball if they are in contact for 6.0 ×10 -3 s?
 A. 14 N B. 2.5 × 10 2 N C. 1.3 × 10 3 N D. 2.3 × 10 3 N

14. A 0.15 kg ball rolls off a bench at 2.4 m/s as shown in the diagram below. What is the vertical component of the ball's momentum when it strikes the floor 0.85 m below? A. 0.36 kg × m/s B. 0.61 kg × m/s C. 0.71 kg × m/s D. 1.2 kg × m/s

15. The front of an automobile is designed to crumple in a collision in order to reduce the injury to the occupants. Discuss briefly the physics of how this design feature improves safety for the occupants. (4 marks) 16. A 5.20 kg block sliding at 9.40 m/s across a horizontal frictionless surface collides head on with a stationary 8.60 kg block. The 5.20 kg block rebounds at 1.80 m/s. How much kinetic energy is lost during this collision? (7 marks)
17. A 4000 kg space vehicle consists of a 2500 kg main capsule and a 1500 kg probe. The space vehicle is travelling at 120 m/s when an explosion occurs between the capsule and the probe. As a result, the probe moves forward at 140 m/s, as shown in the diagram below. a) What is the speed of the main capsule after the explosion? (3 marks)

b) What is the magnitude of the impulse given to the probe? (2 marks)

18. A 5.0 kg object travelling at 1.6 m/s collides with an object of unknown mass m2 travelling at 2.5 m/s. The two objects stick together and move towards the right as shown in the diagram. Find the mass of object m2 . (7 marks)

19. A 3.0 kg car A travelling 8.5 m/s on a frictionless track collides and sticks on to a stationary 2.0 kg car B. a) The combined cars will reach what height h? (5 marks)

b) The steepness of the slope is decreased as shown below. With this decreased slope, the combined cars will reach (circle one) (1 mark)

a) a lesser height.

b) the same height.

c) a greater height.

20. A 7.0 kg object moving at 12 m/s to the east explodes into two unequal fragments. The larger 5.0 kg fragment moves at 15 m/s south. What is the velocity (speed and direction) of the smaller 2.0 kg fragment? (7 marks)

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