Chapter 8 - Momentum

What is impulse?

• A. Change in velocity
• B. Change in momentum
• C. Rate of change of velocity
• D. Rate of change of momentum

In which equation of Newton’s second law is mass assumed to be constant?

• A. F=ma
• B. F= Δp / Δt
• C. F=ΔpΔt
• D. F= Δm / Δa

What is the SI unit of momentum?

• A. N
• B. kg ⋅ m
• C. kg ⋅ m/s
• D. kg ⋅ m/s^2

What is the equation for linear momentum?

• A. p=mv
• B. p=m/v
• C. p=mv^2
• D. p=1/2mv^2

What is an isolated system?

• A. A system in which the net internal force is zero
• B. A system in which the net external force is zero
• C. A system in which the net internal force is a nonzero constant
• D. A system in which the net external force is a nonzero constant

In the equation p_1 + p_2 = p'_1 + p'_2 for the collision of two objects, what is the assumption made regarding the friction acting on the objects?

• A. Friction is zero.
• B. Friction is nearly zero.
• C. Friction acts constantly.
• D. Friction before and after the impact remains the same.

What is an inelastic collision?

• A. when objects stick together after impact, and their internal energy is not conserved
• B. when objects stick together after impact, and their internal energy is conserved
• C. when objects stick together after impact, and always come to rest instantaneously after collision
• D. when objects stick together after impact, and their internal energy increases

Consider two objects of the same mass. If a force of 100 N acts on the first for a duration of 1 s and on the other for a duration of 2 s, which of the following statements is true?

• A. The first object will acquire more momentum.
• B. The second object will acquire more momentum.
• C. Both objects will acquire the same momentum.
• D. Neither object will experience a change in momentum.

Cars these days have parts that can crumple or collapse in the event of an accident. How does this help protect the passengers?

• A. It reduces injury to the passengers by increasing the time of impact.
• B. It reduces injury to the passengers by decreasing the time of impact.
• C. It reduces injury to the passengers by increasing the change in momentum.
• D. It reduces injury to the passengers by decreasing the change in momentum.

How much force would be needed to cause a 17 kg ⋅ m/s change in the momentum of an object, if the force acted for 5 seconds?

• A. 3.4 N
• B. 12 N
• C. 22 N
• D. 85 N