Question 1

A 0.50 kg cue ball is struck by a pool stick and moves left at 3.0 m/s after a collision lasting $$0.00003 s. $$What is the magnitude of the average force exerted by the stick on the ball?

Accepted Answer

$$50,000\ \mathrm{N}$$

Question 2

Which of the following statements about momentum in an isolated system is correct?

Accepted Answer

The total momentum of the system is conserved unless an external force acts on it.

Question 3

A 150 kg crate slides off a 500 kg boat at $$3\ \mathrm{m/s} to $$the right. What is the velocity of the boat immediately after the crate leaves, assuming the system is isolated?

Accepted Answer

$$-0.9\ \mathrm{m/s}$$

Question 4

Which equation correctly expresses the impulse-momentum theorem?

Accepted Answer

$$\sum J = \Delta p$$

Question 5

Three objects have the following momenta: $$p_1 = (-18$$\ \mathrm{kg\cdot m/s}, 0)$$, p_2$ = (-18\ \mathrm{kg\cdot m/s}, 0)$$, $$p_3 = (12$$\ \mathrm{kg\cdot m/s}, -6\ \mathrm{kg\cdot m/s})$$. What is the net momentum vector of the system?

Accepted Answer

$$(-24\ \mathrm{kg\cdot m/s}, -6\ \mathrm{kg\cdot m/s})$$

Question 6

A $$0.5\ \mathrm{kg}$$ egg is tossed into the air with $$2\ \mathrm{kg\cdot m/s} of $$momentum. Which of the following is incorrect?

Accepted Answer

The egg stops moving once $$1\ \mathrm{N\cdot s} of $$momentum is removed.

Question 7

During a collision between two carts of masses $$m_1$$ and $$m_2$$, which of the following is always true?

Accepted Answer

$$m_1$$ \Delta $$v_1$$ = -$$m_2$$ \Delta $$v_2$$

Question 8

A force $$F$$ acts on a $$2\ \mathrm{kg}$$ block for $$3$$ seconds, changing its velocity from $$0 to$$ $$6\ \mathrm{m/s}. $$What is the magnitude of the force?

Accepted Answer

$$4\ \mathrm{kg\cdot m/s} / 3\ \mathrm{s} = 4\ \mathrm{N}$$

Question 9

Which of the following best describes the relationship between impulse and change in momentum?

Accepted Answer

Impulse is equal to the change in momentum: $$J = \Delta p$$

Question 10

A $$3\ \mathrm{kg}$$ object moves at $$(-6\ \mathrm{m/s}, 0)$$, and a $$9\ \mathrm{kg}$$ object moves at $$(-2\ \mathrm{m/s}, 0). $$What is the total momentum in the x-direction?

Accepted Answer

$$-24\ \mathrm{kg\cdot m/s}$$

Question 11

If a net force acts on an object for a time interval $$\Delta t$$, which formula gives the impulse delivered to the object?

Accepted Answer

$$J = F \Delta t$$

Question 12

In a collision between two carts, Cart 1 exerts a force on Cart 2 for a time $$\Delta t. $$What is the change in momentum of Cart 2?

Accepted Answer

$$\Delta p_2$ = F_{1\ on\ 2} \Delta t$$

Question 13

A $$0.5\ \mathrm{kg}$$ ball falls under gravity. What is the impulse delivered by gravity in $$1$$ second?

Accepted Answer

$$4.9\ \mathrm{N\cdot s}$$

Question 14

Which of the following is a correct statement about the conservation of momentum in a two-object collision?

Accepted Answer

The total momentum before the collision equals the total momentum after the collision.

Question 15

A $$2\ \mathrm{kg}$$ cart moving at $$5\ \mathrm{m/s}$$ collides with a stationary $$3\ \mathrm{kg}$$ cart. If the system is isolated, what is the total momentum after the collision?

Accepted Answer

$$10\ \mathrm{kg\cdot m/s}$$

Question 16

A force of $$4\ \mathrm{N}$$ acts on a block for $$2$$ seconds. What is the change in momentum of the block?

Accepted Answer

$$8\ \mathrm{kg\cdot m/s}$$

Question 17

Which of the following is NOT a requirement for momentum conservation in a system?

Accepted Answer

The system must have objects of equal mass.

Question 18

A $$1\ \mathrm{kg}$$ ball moving at $$2\ \mathrm{m/s}$$ collides with a $$2\ \mathrm{kg}$$ ball at rest. After the collision, the $$1\ \mathrm{kg}$$ ball moves at $$0.5\ \mathrm{m/s}. $$What is the velocity of the $$2\ \mathrm{kg}$$ ball after the collision?

Accepted Answer

$$0.75\ \mathrm{m/s}$$

Lecture 10

Study Guide - Practice Questions

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