Momentum Review PHY 1718
Part I Conceptual Review
1. Be able to apply the momentum impulse theorem to the following types of situations:
a. Whys airbags keep you safe in a collision
b. Why a boxer rolls with a punch
c. Why a loaded down big rig takes a lot longer to stop than one without a trailer
d. Why the harder you brake, the faster you stop
2. Describe how velocity changes in the following situations:
a. Two skaters are standing still, then push off each other
b. When a moving car hits a stationary car. The first car stops and the second car moves.
3. If a moving object hits a stationary object and they stick together, describe the motion of the two objects after the collision.
Part II Calculations
1. Be able to calculate simple momentum problems such as:
a. If a 35 kg ball is rolling with a speed of 15 m/s, what is its momentum?
b. An object is traveling at 20 m/s with a momentum of 88kgm.s. What is the mass of the object?
c. How fast is an 85 kg object going if it has a momentum of 1500kgm/s?
2. Be able to use the momentum impulse theorem to solve questions such as:
a. A 500 kg truck brakes using a 9000 N of force. If it is traveling at a speed of 35 m/s, how long will it take the truck to stop?
b. How much force is required to stop a 675 kg car that is going 50 m/s in 3 sec?
c. You are driving your 550 kg vehicle at 15 m/s when you accelerate by applying 350 N of force for 10 s. What is the new speed at which you are traveling? Challenge question
d. A 0.20 kg soccer ball is travelling towards you at 4.7 m/s. If you kick it with 35 N of force, and it causes the ball to travel at 5.1 m/s in the opposite direction, how long was the ball in contact with your foot?
3. Be able to use conservation of momentum to solve questions such as:
a. A 1500 kg car is stuck on a railroad track. A 40000 kg train collides with the car. The car and train stick together and move forward with the same velocity of 8 m/s after the collision. What was the initial velocity of the train?
b. You roll an 8.5 kg bowling ball at a speed of 6 m/s so that it hits a stationary 0.25 kg golf ball. If the golf ball has a speed of 18 m/s after the collision, how fast is the bowling ball traveling after the collision?
c. A red ball with a mass of 3.6 kg is traveling at 5 m/s. A green ball with a mass of 4.8 kg is traveling at 7 m/s towards the red ball. After the collision the red ball bounces off in the opposite direction at a velocity of 8.71 m/s. What is the final velocity and direction of the green ball?
d. A 20 kg cannonball is at rest in a 1750 kg cannon. After shooting the cannonball forwards, the cannon has a backwards velocity of 1.8 m/s. What is the final velocity of the cannonball? Challenge question