Q: Which of the following best describes the relationship between impulse and change in momentum for an object?

$$\vec{J} = \vec{F}_{\text{net}} \cdot \Delta t = \Delta \vec{p}$$

Q: Which of the following is the correct expression for the total linear momentum of a system of $$N$$ objects?

$$\vec{p}_{\text{tot}} = \sum_{i=1}^{N} \vec{p}_i$$

Question 1

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

Accepted Answer

$$\vec{J} = \vec{F}_{	ext{net}} \cdot \Delta t = \Delta \vec{p}$$

Question 2

A 0.05 kg golf ball strikes a hard floor at an angle of $$30^\circ$$ with a speed of $$40\ 	ext{m/s}$$ before and after bouncing. What is the magnitude of the impulse delivered by the floor to the ball?

Accepted Answer

$$2\ 	ext{Ns}$$

Question 3

If the kinetic energy $$K of a $$particle of mass $$m is $$quadrupled, what happens to its linear momentum?

Accepted Answer

It is doubled.

Question 4

Two balls identical in mass and shape are dropped from the same height. In Case 1, the ball bounces off the floor; in Case 2, the ball sticks to the floor. In which case does the linear momentum change more?

Accepted Answer

It changes more in Case 1.

Question 5

On a countryside road, you are about to lose control of your car. In your path are a haystack and a stone wall side by side. You try to direct your car toward the haystack because:

Accepted Answer

You will receive a smaller average force.

Question 6

Which of the following is the correct expression for the total linear momentum of a system of $$N$$ objects?

Accepted Answer

$$\vec{p}_{	ext{tot}} = \sum_{i=1}^{N} \vec{p}_i$$

Question 7

Two 180-g hockey pucks are moving towards each other with the same speed on a collision course. What is their total linear momentum?

Accepted Answer

$$0$$

Question 8

A 54-kg woman and an 81-kg man are initially at rest on frictionless ice. The woman pushes off and moves away at $$+2.2\ 	ext{m/s}. $$What is the velocity of the man at the same instant?

Accepted Answer

$$-1.47\ 	ext{m/s}$$

Question 9

You jump from rest by pushing against the ground with your legs. Which statement is true about the Earth?

Accepted Answer

It moves down with lower speed than yours.

Question 10

Which of the following is true for an isolated system?

Accepted Answer

The sum of the external forces acting on the system is zero.

Question 11

Which condition must be met for the conservation of linear momentum in a collision?

Accepted Answer

The net external force on the system is zero.

Question 12

In an elastic collision between two objects, which of the following is conserved?

Accepted Answer

Both total linear momentum and total kinetic energy.

Question 13

A pellet of mass $$0.01\ 	ext{kg} is $$fired into a $$1.05\ 	ext{kg}$$ block of clay at rest. After the collision, the clay and pellet move together at $$0.52\ 	ext{m/s}. $$What was the initial speed of the pellet?

Accepted Answer

$$55\ 	ext{m/s}$$

Question 14

Two balls of clay roll towards each other, collide, and stick. The first has a mass of $$5\ 	ext{kg}$$ and is traveling $$13\ 	ext{m/s}$$ South. The second has a mass of $$2\ 	ext{kg}$$ and is traveling $$24\ 	ext{m/s}$$ East. What is the magnitude of the velocity of the clay immediately after impact?

Accepted Answer

$$11.6\ 	ext{m/s}$$

Question 15

A 0.17 kg cue-ball is launched directly towards a stationary 9-ball (0.16 kg) at $$9\ 	ext{m/s}. $$After the collision, the cue ball is deflected $$20^\circ to $$the left and has a speed of $$6\ 	ext{m/s}. $$How fast is the 9-ball moving immediately after impact?

Accepted Answer

$$4.2\ 	ext{m/s}$$

Question 16

A satellite orbits the Earth at constant speed. What can we assume about its net force?

Accepted Answer

$$F_{	ext{net}} \u003e 0$$

Question 17

Imagine a ball attached to a string is being swung in a horizontal circle. If the string suddenly breaks, which path most accurately describes the subsequent motion of the ball?

Accepted Answer

It moves tangentially to the circle at the point of release.

Question 18

The instantaneous velocity of an object in circular motion is:

Accepted Answer

Tangent to the circular path.

Question 19

A kid on the edge of a carousel experiences half a revolution in $$11\ 	ext{s}. If $$the radius of the carousel is $$4\ 	ext{m}$$, what is the kid's tangential speed?

Accepted Answer

$$1.14\ 	ext{m/s}$$

Question 20

How does the angular speed of a point on the edge ($$r) of a $$carousel compare to the angular speed at a point located a distance of $$r/2$$ from the center?

Accepted Answer

$$\omega_r = \omega_{r/2}$$

Momentum, Impulse, and Circular Motion: Study Notes

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