Q: Which of the following is the correct expression for the impulse-momentum theorem for linear motion?

$$F_{\text{net}} \Delta t = m \Delta v$$

Question 1

A 0.80 kg falcon dives at $$18\ \mathrm{m/s} at a$$ $$45^\circ$$ angle below the horizontal and catches a $$0.36\ \mathrm{kg}$$ pigeon flying horizontally at $$9.0\ \mathrm{m/s}. $$Immediately after the perfectly inelastic collision, what is the magnitude of their common velocity?

Accepted Answer

$$15\ \mathrm{m/s}$$

Question 2

Which of the following statements best describes the conservation of momentum in two-dimensional collisions?

Accepted Answer

The x- and y-components of the total momentum are conserved separately.

Question 3

A 500 g ball traveling to the right at $$4.0\ \mathrm{m/s}$$ collides and bounces off another ball that is initially at rest. After the collision, the first ball moves at $$2.0\ \mathrm{m/s} at a$$ $$60^\circ$$ angle above the horizontal. What is the magnitude of the momentum of the second ball after the collision?

Accepted Answer

$$1.73\ \mathrm{kg\cdot m/s}$$

Question 4

Which equation correctly expresses the conservation of angular momentum for a system of two objects with moments of inertia $$I_1$$ and $$I_2$$ and angular velocities $$\$$omega_1$$ and $$\$$omega_2$$?

Accepted Answer

$$I_1$$\$$omega_1$$ + $$I_2$$\$$omega_2$$ = $$I_1$$\$$omega_1$$' + $$I_2$$\$$omega_2$$'$$

Question 5

A merry-go-round (uniform disk, $$M=200\ \mathrm{kg}$$, $$R=2.0\ \mathrm{m}) $$rotates once every $$2.5\ \mathrm{s}. $$Joey ($$m=36\ \mathrm{kg}) $$stands at the center and walks to the edge. What is the new period of rotation when Joey reaches the edge?

Accepted Answer

$$3.4\ \mathrm{s}$$

Question 6

Which of the following best explains why a figure skater spins faster when pulling in their arms?

Accepted Answer

Their moment of inertia decreases, so angular velocity increases to conserve angular momentum.

Question 7

A bicycle wheel (mass $$1.5\ \mathrm{kg}$$, radius $$0.33\ \mathrm{m}) $$spins at $$14\ \mathrm{rad/s}. $$What is the angular momentum of one wheel, assuming all mass is at the rim?

Accepted Answer

$$2.2\ \mathrm{kg\cdot m^2$/s}$$

Question 8

Which of the following is the correct SI unit for angular momentum?

Accepted Answer

$$\mathrm{kg\cdot m^2$/s}$$

Question 9

A system is isolated if:

Accepted Answer

The net external force is zero.

Question 10

Which of the following is the correct expression for the impulse-momentum theorem for linear motion?

Accepted Answer

$$F_{	ext{net}} \Delta t = m \Delta v$$

Question 11

A $$2.0\ \mathrm{kg}$$ object at rest explodes into three fragments. Two fragments have momenta $$\vec{p}_1 = (2, 0)\ \mathrm{kg\cdot m/s}$$ and $$\vec{p}_2 = (0, 3)\ \mathrm{kg\cdot m/s}. $$What is the momentum of the third fragment?

Accepted Answer

$$(-2, -3)\ \mathrm{kg\cdot m/s}$$

Question 12

Which of the following is true for a perfectly inelastic collision?

Accepted Answer

Momentum is conserved, but kinetic energy is not.

Question 13

If the net external torque on a system is zero, what can be said about the system's angular momentum?

Accepted Answer

It is conserved.

Question 14

A rotating object has a moment of inertia $$I$$ and angular velocity $$\omega. $$What is its angular momentum?

Accepted Answer

$$I\omega$$

Question 15

A $$0.80\ \mathrm{kg}$$ falcon dives at $$18\ \mathrm{m/s} at$$ $$45^\circ$$ below the horizontal and catches a $$0.36\ \mathrm{kg}$$ pigeon flying horizontally at $$9.0\ \mathrm{m/s}. $$What is the direction of their velocity immediately after impact?

Accepted Answer

$$37^\circ$$ below the horizontal

Question 16

Which of the following best describes the effect of increasing the moment of inertia of a rotating system with no external torque?

Accepted Answer

The angular velocity decreases.

Question 17

Which of the following is the correct analogy between linear and rotational dynamics?

Accepted Answer

Force is to mass as torque is to moment of inertia.

Question 18

A system of two objects is rotating with no net external torque. If the moment of inertia of one object decreases, what happens to its angular velocity?

Accepted Answer

It increases.

Question 19

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

Accepted Answer

The system must be at rest.

Momentum, Collisions in Two Dimensions, and Angular Momentum: Study Notes

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