Name _____ KEY ____________________________________ Date _________ Period ______
Conservation of Energy
1.
Compare the energy of an object at the top of a hill to its energy at the bottom of the hill.
What has changed and what has stayed the same?
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2.
The total energy is the same at the top and bottom, but the object has all
potential energy at the top of the hill, and kinetic energy at the bottom.
A 22 kg ball is tossed straight up with a kinetic energy of 757 J. How high does it go?
PEtop = KEbottom = 757 J
3.
You are on roller blades on top of a small hill. Your potential energy is 1000. J and your
mass is 60.0 kilograms.
a. What is the height of the hill?
b. What will be your speed at the bottom of the hill?
KEbottom = PEtop = 1000. J
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4.
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A 500 kg roller coaster car starts from rest at the top of a 60.0 m hill.
a. What is the potential energy at the top?
PE = mgh = (500 kg)(9.8 m/s2)(60.0 m) = 294,000 J
b. Find its potential and kinetic energies when it is halfway to the bottom.
PE = KE = ½ PEtop = 147,000 J
5.
In lab, your group measures the speed of a 0.100
starting position at the top of the hill is 1.00 m.
car at t e botto
of a ill T e car’
a. What is the potential energy of the car at the beginning of the experiment before
its speed is measured?
PE = mgh = (0.100 kg)(9.8 m/s2)(1.00 m) = 0.98 J
b. Calculate the kinetic energy of the car at the bottom of the hill.
KEbottom = PEtop = 0.98 J
c. Calculate the speed of the car at the bottom of the hill.
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