Physics 30: Chapter 2 Exam



Physics 30: Chapter 2 Exam – Momentum & Impulse

Name: _________________________ Date: _____________ Mark: ____/29

Numeric Response. Place your answers to the numeric response questions, with units, in the blanks at the side of the page. (1 mark each)

|1. |A golfer putts a 45.7 g golf ball at speed of 1.10 m/s along a level green. Determine the magnitude | | |

| |of the ball’s momentum. | | |

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|2. |A 20 g ball is dropped from a height of 1.2 m. Determine its momentum just as it hits the ground. | | |

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|3. |A curler slides a 20 kg curling rock at a speed of 2.0 m/s. The rock is caught by a stationary 55 kg | | |

| |player. If frictional losses are ignored, determine the speed of the player immediately after | | |

| |catching the rock. | | |

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|4. |A 10 kg mass moving with a kinetic energy of 150 J collides with a 15 kg mass having a kinetic energy| | |

| |of 100 J. Assuming the collision is inelastic and the 10 kg mass has 90 J of kinetic energy after the| | |

| |collision. Determine the amount of kinetic energy possessed by the 15 kg mass after the collision if | | |

| |80 J of heat energy is released during the collision. | | |

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Written Response. Show all your work. Clearly identify your final answer(s) rounded off to the proper number of significant digits.

1. A 12 kg mass is sliding due east at 2.0 m/s when it collides with a stationary 10 kg mass. After the collision the 12 kg mass is moving with a velocity of 1.2 m/s, 24° S of E.

a. Determine the velocity of the 10 kg mass after the collision. (5 marks)

b. Show that the collision was inelastic. (2 marks)

Multiple Choice. Select the best answer and mark it clearly on your Scantron. (1 mark each)

1. An alpha particle (6.65 x 10-27 kg) is travelling at 4.50 x 106 m/s. The magnitude of its momentum is

|a. |2.99 x 10-20 kg•m/s |

|b. |1.48 x 10-33 kg•m/s |

|c. |2.99 x 10-22 kg•m/s |

|d. |1.48 x 10-22 kg•m/s |

2. A 400 g ball is dropped from a height of 95 cm. Calculate the magnitude of its momentum as it makes contact with the floor.

|a. |1.7 kg•m/s |

|b. |4.3 kg•m/s |

|c. |7.5 kg•m/s |

|d. |17 kg•m/s |

3. A 640 g toy car moving east has a kinetic energy of 0.348 J. The magnitude of its momentum is

|a. |0.667 kg•m/s |

|b. |0.223 kg•m/s |

|c. |0.696 kg•m/s |

|d. |0.472 kg•m/s |

4. A baseball has a momentum of 3.0 kg(m/s north before it is hit. Determine the impulse acting on the ball while it is being hit if its momentum after being hit is 5.0 kg(m/s to the south.

|a. |2.0 N•s to the north |

|b. |2.0 N•s to the south |

|c. |8.0 N•s to the north |

|d. |8.0 N•s to the south |

Use the following information to answer questions 5 & 6.

A 150 g baseball is pitched horizontally to the north at a speed of 30.0 m/s. After the batter hits the ball it moves horizontally to the south at a speed of 30.0 m/s.

5. Determine the magnitude of the impulse transferred to the ball.

|a. |0 N•s |

|b. |4.5 N•s |

|c. |9.0 N•s |

|d. |135 N•s |

6. Determine the magnitude of the average force exerted on the ball by the bat if they were in contact for 0.900 s.

|a. |10.0 N |

|b. |150 N |

|c. |135 N |

|d. |5.00 N |

7. A pendulum is released from a vertical height of 30 cm. The maximum momentum of the pendulum can be found using the expression

|a. |p = m |

|b. |p = m |

|c. |p = |

|d. |p = m |

8. The units of momentum can be expressed as

|a. |kg•m/s2 |

|b. |N/s |

|c. |N•m/s |

|d. |kg•m/s |

Use the information below to answer question 9.

The graph below shows the net force of a paddle in water causing a kayak to travel along a still lake.

9. The net impulse on the paddle is

|a. |230 kN•s |

|b. |460 kN•s |

|c. |500 kN•s |

|d. |540 kN•s |

10. Impulse may be defined as

|a. |An objects’ momentum |

|b. |The work done on an object per unit time |

|c. |A product of force and time |

|d. |Force per unit time |

11. Identify the list below that contains only conserved quantities.

|a. |Energy, acceleration, forces |

|b. |Energy, momentum, velocity |

|c. |Momentum, mass, energy |

|d. |Momentum, velocity, forces |

Use the following information to answer question 12.

Ballistic pendulums used to be used to determine a firearm’s muzzle velocity. A ballistic pendulum is constructed by hanging a block of wood by two wires; the wires allow the block to swing freely like a pendulum.

A 3.50 kg rifle fires a 20.0 g bullet into a ballistic pendulum as shown in the diagram below. The bullet buries itself in the 1.80 kg ballistic pendulum, and they rise to a vertical height of 0.350 m.

[pic]

12. Determine the bullet’s muzzle velocity (i.e., speed the bullet leaves the rifle barrel).

|a. |2.62 m/s |

|b. |236 m/s |

|c. |238 m/s |

|d. |262 m/s |

13. Two identical air pucks collide at right angles and stick together. Each has a momentum of 2.0 kg•m/s before the collision. Determine the magnitude of their momentum after the collision if they stick together upon impact.

|a. |2.0 kg•m/s |

|b. |2.8 kg•m/s |

|c. |4.0 kg•m/s |

|d. |8.0 kg•m/s |

14. Identify the true statement below.

|a. |kinetic energy and momentum are both conserved in inelastic collisions |

|b. |only kinetic energy is conserved in elastic collisions |

|c. |kinetic energy and momentum are both conserved in elastic collisions |

|d. |only momentum is conserved in elastic collisions |

Use the information below to answer question 15.

A toy contains three different springs that cause the toy to come apart into three identical pieces that all move along the floor as shown in the diagram below.

15. Predict the direction travelled by the third piece of the toy.

|a. |74° S of E |

|b. |87° E of N |

|c. |13° N of W |

|d. |87° N of E |

Use the information below to answer questions 16 & 17.

A 40 kg mass moving with a kinetic energy of 200 J collides with a 15 kg mass having a kinetic energy of 180 J.

16. Assume the collision is completely elastic and the 40 kg mass has 180 J of kinetic energy after the collision. Determine the amount of kinetic energy possessed by the 15 kg mass after the collision.

|a. |0 |

|b. |20 J |

|c. |180 J |

|d. |200 J |

17. Assuming the collision is inelastic and the 40 kg mass has 130 J of kinetic energy after the collision. Determine the amount of kinetic energy possessed by the 15 kg mass after the collision if 100 J of heat energy is released during the collision.

|a. |0 |

|b. |50 J |

|c. |150 J |

|d. |230 J |

Use the following information to answer question 18.

A stone is thrown straight up into the air and falls under the influence of gravity. The following six graphs may represent the stone’s motion as it travels freely through the air (ignore air resistance).

|[pic] | |[pic] |

|[pic] |[pic] |[pic] |

18. Identify the graph that best displays the momentum of the stone as a function of time.

|a. |F |

|b. |D |

|c. |A |

|d. |E |

-----------------------

1.0

2.0

Time (s)

Force (kN)

500

-500

0

Net Force versus Time

t

B

2.0 m/s

3.0 m/s

N

45°

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