# Physics Study Guide Momentum

**Physics Study Guide Momentum**

**Solve the following problems.**

- A car has a mass of 725 kg and is moving at a speed of 100 km/hr.
- Find its momentum.
- At what velocity is the momentum of a larger car with a mass of 2175 kg equal to that of the smaller car?
- The brakes exert a 6.40 x 102 N force on a car weighing 15680 N and moving at 20 m/s. The car finally stops.
- What is the car’s mass?
- What is the initial momentum?
- What is the change in the car’s momentum?
- How long does the braking force act on the car to bring it to a halt?
- A 35 g bullet strikes a 5 kg stationary wooden block and embeds itself in the block. The block and bullet fly off together at 8.6 m/s. What was the original velocity of the bullet?
- A 35 g bullet strikes the radiator of a 1245 kg car driving towards the person with the gun. The bullet’s initial velocity is the same as the bullet in problem number 5. The final velocity of the car and bullet is –60 m/s. What was the initial velocity of the car?
- A 4 kg model rocket is launched, shooting 50 g of burned fuel from its exhaust at an average velocity of 625 m/s. What is the velocity of the rocket after the fuel has burned? (Ignore effects of gravity and air resistance.)
- A thread holds two carts together on a frictionless surface. Cart one has a mass of 1.5 kg and cart two has a mass of 4.5 kg. A compressed spring acts upon the carts. After the thread is burned, the 1.5 kg cart moves with a velocity of 27 cm/s to the left. What is the final velocity of the 4.5 kg cart?
- A stationary billiard ball, mass 0.17 kg, is struck by an identical ball moving at 4 m/s. After the collision, the second ball moves off at 60o to the left of its original direction. The stationary ball moves off at 30o to the right of the second ball’s original direction. What is the velocity of each ball after the collision?
- An eighteen-wheeler is driving East on Highway 6 at a speed of 90 km/hr. The mass of the truck is 4000 kg. An inattentive motorcycle driver is riding his hog West on Highway 6 on the wrong side of the road. The mass of the motorcycle is 533 kg. The two vehicles crash into each other. When the two hit, they both stop cold.
- What is the initial momentum of the truck?
- What speed must the motorcycle been traveling before they crashed for them to have stopped cold?
- A jet ski has a mass of 2.50 x 102 kg. A constant force is exerted on it for 60 s. The Jet Ski’s initial velocity is 6 m/s and its final velocity 28 m/s.
- What is its change in momentum?
- What is the magnitude of the force exerted on it?
- A 35 g bullet strikes an 8 kg stationary wooden block and embeds itself in the block. The block and bullet fly off together at 7.3 m/s. What was the original velocity of the bullet?
- A 35 g bullet strikes the radiator of a 1245 kg car driving towards the person with the gun. The bullet’s initial velocity is the same as the bullet in problem number 10. The final velocity of the car and bullet is –60 m/s. What was the initial velocity of the car?
- A 4 kg model rocket is launched, shooting 50 g of burned fuel from its exhaust at an average velocity of 786 m/s. What is the velocity of the rocket after the fuel has burned? (Ignore effects of gravity and air resistance.)
- A thread holds two carts together on a frictionless surface. Cart one has a mass of 1.5 kg and cart two has a mass of 4.5 kg. A compressed spring acts upon the carts. After the thread is burned, the 1.5 kg cart moves with a velocity of 45 cm/s to the left. What is the final velocity of the 4.5 kg cart?
- A billiard ball, mass 0.17, strikes an identical ball moving towards it at 3 m/s. After the collision, the first ball moves off at 43o left of its original direction with a speed of 2.5 m/s. The second ball moves off 90o to the new direction of the first ball with a speed of 4.6 m/s. What was the initial velocity of the first ball?