Physics 11 Final Review: Momentum & Energy
Impulse & Momentum
1. Calculate the momentum of a 120 g robin flying with a speed of 10 m/s
2. Which has the greater momentum: a 145 g baseball travelling at 40.0 m/s or a 45 g golf ball
travelling at 67.0 m/s? How much greater?
3. What impulse is needed to stop a 45 g mass travelling at 42 m/s?
4. A force of 540 N is used to stop an object with a mass of 65 kg moving 175 m/s. How long
will it take the object to come to a full stop?
5. In hitting a stationary hockey puck having a mass of 180 g, a hockey player gives the puck
an impulse of 6.0 N.s. At what speed will the puck move toward the goal?
6. A snowball with a mass of 85 g hits a snowman's top hat and sticks to it. The hat and the
snowball, with a combined mass of 220 g, fall off together at 8.0 m/s. How fast was the
snowball moving at the moment of impact?
7. A ball of mass 12 g moving at 15 m/s collides with a second ball of mass 36 g moving at 5 m/s.
After the collision, the 12 g ball moves at 6 m/s. Find the new speed and the change in
momentum of the 36 g ball.
8. A 24.0 kg dog running at a speed of 3.0 m/s jumps onto a stationary skateboard that has a
mass of 3.6 kg.
a) Find the speed of the dog on the skateboard.
b) How long will it take an average force of 9.0 N to stop the skateboard and dog?
Work & Energy
1. What is the kinetic energy of a body of mass 2.0 kg, moving with a speed of 3 m/s?
2. A 50 kg person climbs a flight of stairs 10 m high. How much work was done?
3. A 200 kg crate rests on the floor. How much work is done to move it 15 m along the floor
at constant speed against a friction force of 700 N?
4. A grocer lifts an 8.0 kg carton from the floor to a height of 0.80 m, carries it 24 m across the store, and places it on a shelf 1.8 m above the floor. How much work is done by the grocer?
5. How high must a 1000 kg pile driver be lifted if it is to do 150 000 J of work?
6. A 100 kg rocket has 40 000 000 J of kinetic energy. How fast is it moving?
7. A 15 kg monkey swings from one branch to another 2.0 m higher; what is its change in
potential energy?
8. A 2.0 kg rock is thrown downward with a speed of 10 m/s from the top of a 30 m high
cliff. With what speed does it hit the ground below?
9. A 115 kg man runs up a 3.0 m high flight of stairs in 5.0 s. What power does he use?
10. How much power is generated by a machine in moving a 250 kg mass a distance of 150 m vertically in 30.0 s?
11. a) Explain why it is more accurate to use conservation of momentum equations to solve
for collisions and explosions problems than conservation of energy equations.
b) Under what circumstances can conservation of energy equations be used to solve
such problems?
Thermal Energy
1. How much heat is required to raise the temperature of 250 grams of water from 20°C to 35°C?
(sp. heat of water = 4180 J/kg*°C)
2. If 1.5 x 104 J of heat are absorbed by a 15 kg aluminum ladder leaning against a sunny
wall, by how much will the temperature rise? (sp. heat of aluminum = 903 J/kg*°C)
3. Explain the difference between thermal energy, heat and temperature.
4. a) Explain why 0 K is the lowest possible temperature.
b) What are the Kelvin and Celsius scales based on?
5. When a 0.050 kg piece of material at 95°C is dropped into 0.250 kg of water initially
at 17°C, the temperature of the water rises to 19.4°C. Calculate the specific heat of
the material.