Review Classwork 4: Work Energy Momentum
Name:__________________
**Must include explanation / work for credit**
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2. A baseball is tossed straight up in the air. Which of the following is true about the kinetic energy of
the baseball the moment it reaches maximum height?
a. At that instant, the baseball’s kinetic energy is greater than zero.
b. At that instant, all the baseball’s kinetic energy has been lost as heat to the atmosphere.
c. At that instant, all the baseball’s kinetic energy has been converted to potential energy.
d. At that instant, the baseball’s kinetic energy is less than zero.
3. A rollerskater loses control and slides into a pile of leaves with a velocity of 8.0 m/s. If the rollerskater is
brought to a rest in 0.40 seconds, what is the magnitude of the average force exerted on the rollerskater by
the pile of leaves?
4. An archer performs 80. J of work in pulling back the string of a bow. What will be the initial speed of a 0.40
kg arrow when it is fired from the bow?
5. Student A lifts a 50. N box from the floor to a height of 1.0 m in 1.2 seconds. Student B lifts a 30. N box
from the floor to a height of 1.2 m in 1.5 seconds.
a) Which student does more work?
b) Which student develops more power?
6. A 1.0 kg clay ball is rolled to the right with a speed of 5.0 m/s towards a 2.0 kg wooden block that is initially
at rest. After the collision, the clay ball and the wooden block stick together and move to the right. What is
their speed?
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