Name
Date
Momentum
Conservation of Momentum
Instructions: Do every problem using LEPA on a separate sheet of paper.
1. An 8.0-kilogram cart moving to the right at 4.0 meters per second about to make a headon collision with a 4.0-kilogram cart moving to the left at 6.0 meters per second. After
the collision, the 4.0-kilogram cart moves to the right at 3.0 meters per second. What is
the velocity of the 8.0-kilogram cart after the collision? 0.5 m/s left
2. Two masses are separated by a compressed spring. The spring is released, pushing both
objects outward from rest. A 3 kg mass is thrown to the left at 8 m/s. What is the speed
of the 2 kg mass that was pushed to the right? 12 m/s
3. A 1.0 kilogram laboratory cart moving with velocity of 0.5 meter per second due east
collides with and sticks to a similar car initially at rest. After the collision, the two carts
move off together with a velocity of 0.25 meter per second due east. The total
momentum of this frictionless system is
a. zero before the collision
b. zero after the collision
c. the same before and after the collision
d. greater before the collision than after the collision
4. An explosion blows a 15-kg object into two pieces. A 5-kg piece is shot to the right at 20
m/s. What is the speed of the other piece? 10 m/s
5. A 4-kilogram mass is moving at 3.0 meters per second toward the right and a 6.0kilogram mass is moving at 2.0 meters per second toward the left on a horizontal
frictionless table. What is their final momentum, if the two masses remain together after
the collision?
6. A 4-kilogram rifle fires a 0.02-kilogram bullet with a velocity of 300 m/s. Find the recoil
velocity of the rifle. 1.5 m/s
7. A 2.0 kilogram toy cannon is at rest on a frictionless surface. A remote triggering device
causes a 0.005 kilogram projectile to be fired from the cannon. Which equation describes
this system after the cannon is fired?
a. mass of cannon + mass of projectile = 0
b. speed of cannon + speed of projectile = 0
c. momentum of cannon + momentum of projectile = 0
d. velocity of cannon + velocity of projectile = 0
8. In a lab, two 0.75 kg carts are hooked together with a spring between them. The carts are
pushed to the right and roll at a speed of 1.5 m/s. The spring goes off and pushes the two
carts apart. If one of the carts stops, what is the speed of the other cart? 3 m/s
9. An object with mass m is traveling at a velocity v towards an object with a mass M that is
at rest. After the collision the two objects stick together. What is the velocity, va, after
the collision?
10. Jan 2002 Regents question: The diagram below shows two carts that were initially at rest
on a horizontal, frictionless surface being pushed apart when a compressed spring
attached to one of the carts is released. Cart A has a mass of 3 kg and cart B has a mass
of 5 kg. If the speed of cart A is 0.33 meter per second after the spring is released, what
is the approximate speed of cart B after the spring is released? 0.2 m/s