Physics 1.22: 7.1.1 Momentum

Multiple Choice

How do these balls compare in terms of momentum just before the goalie stops them?

• They have the same momentum.

• The soccer ball has more momentum.

• The bowling ball has more momentum.

Multiple Choice

A cougar runs with a velocity of 8.0 m/s west. If the cougar has a momentum of 352 kg·m/s, what is its mass? (p = mv)

• 87 kg

• 28 kg

• 44 kg

• 0.020 kg

Multiple Choice

The mass of an arrow is 0.01 kg, and it has a momentum of 0.2 kg·m/s to the left. What is the velocity of the arrow? $$\left(p\ =\ mv\right)$$

• 10 m/s left

• 30 m/s left

• 40 m/s left

• 20 m/s left

Multiple Choice

A wrestler falls to the ground during a match. When he hits the floor, his speed changes from 8 m/s to 0 m/s. If his mass is 115 kg, what is the impulse applied by the floor? ( $$I\ =\ m\Delta v$$ )

• 920 kg∙m/s

• –920 kg∙m/s

• –850 kg∙m/s

• –770 kg∙m/s

Multiple Choice

A submarine is traveling underwater at a speed of 8 m/s. The submarine and its crew have a combined mass of 7 × 10^6 kg. If the submarine speeds up to 9.5 m/s, how much impulse is supplied by the submarine's engines? $$\left(I\ =\ m\Delta v\right)$$

• 7.5 × 10^6 kg∙m/s

• 5.6 × 10^7 kg∙m/s

• 1.05 × 10^7 kg∙m/s

• 6.65 × 10^7 kg∙m/s

Poll

If you wear kneepads while skating, it will take 3 times as long for you to come to rest when you fall and land on your knees. How does this affect the impulse applied to your knees when you fall?

• I think the impulse will decrease.

• I think the impulse will increase.

• I think the impulse will not change.

Multiple Choice

Imagine you are an action movie star who is trying to break down a door by jumping into it. You have a mass of 80 kg, and you jump against the door with a speed of 6 m/s. If your velocity drops to zero in 0.2 seconds, how much force do you exert on the door? $$\left(F\Delta t\ =\ m\Delta v\right)$$

• -1600 N

• -2400 N

• -3200 N

• -3800 N

Multiple Choice

You exerted a force of -2400 N. How much force do you exert on the door if you bounce back at a speed of 2 m/s? (Mass = 80 kg, initial speed is 6 m/s, and the time of impact is still 0.2 seconds.) $$\left(F\Delta t\ =\ m\Delta v\right)$$

• -3200 N

• -3000 N

• -2800 N

• -1600

Multiple Choice

Air bags are standard car safety features. The air bag reduces the force of a collision by increasing the time of impact. Without an air bag, a 70 kg driver going 25 m/s would experience a force of 12,000 N. If the airbag increases the time of impact by 8.5, how much force does the driver experience with the air bag? $$\left(F\Delta t\ =\ m\Delta v\right)$$

• 1412 N

• 2344 N

• 12,000 N

• 102,558 N