Physics 8
Name ________________________
Chapter 15.2 Lab
Date Started _________ Period ___
Due date ___________
Energy Conversion and Energy Conservation
Introduction: As a cart rolls down an inclined plane, the mechanical potential
energy of the cart is converted to mechanical kinetic energy. Frictional forces
cause a loss of kinetic energy.
CONVERSION (energy changes from one form to another): During this class
activity, you will take measurements to find the mechanical potential energy
converted to mechanical kinetic energy by the moving cart.
CONSERVATION (energy cannot be created or destroyed): You will then compare
mechanical potential energy to mechanical kinetic energy to see the loss of
energy due to frictional forces.
Equations:
𝑃𝐸 = 𝑚𝑔ℎ
𝑣=
𝑑
𝑡
𝐾𝐸 =
1
2
𝑚 𝑣2
Distance the car
traveled ______m
Height
= ___
Physics 8 15.2 PE KE ramp conversions 3.2013
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Procedure for Energy Conversion:
1. Find the Potential energy of the cart at the top of the ramp. Measure the
height of the ramp. Convert units to meters if needed.
Record the height of the ramp = _________ m
2. Measure the mass of the cart using a triple-beam balance. Careful to zero
the balance, and measure properly. Convert mass to kg if needed.
Record the mass of the cart = _________ kg
Calculate the potential energy of the cart at the top of the ramp. Show the
E.S.A. in the box below. Have the answer to the 0.0001 place. g = 9.8 m/s2
Strategy: Measure the velocity of the cart; calculate the kinetic energy of the cart
at the bottom of the ramp.
3. Measure the length of the ramp. Convert to meters if needed.
Record the length of ramp = ________ m
4. Set the cart at the top of the ramp, ready the stopwatch. Measure the time
for the cart to reach the bottom of the ramp in seconds to the .01s place.
Record 3 trials: 1.__________ 2. _________ 3.___________
Calculate the average time. Record the average of the 3 time trials = _____s
5. Calculate the velocity of the cart. Have the answer to the 0.0001 place.
Show the E.S.A. in the box below.
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6. Calculate the kinetic energy of the cart at the bottom of the ramp.
Show the E.S.A. in the box below. Have the answer to the 0.0001 place.
Energy Conservation
Procedure for measuring Conservation of Energy (Example)
(KE + PE) beginning of action – friction = (KE + PE) end of action
100J
- 5J
95J
=
=
95J
95J
The cart was not moving at the top of the ramp, all of the
mechanical energy was in the form of potential energy. Since the
cart was moving the fastest and at the lowest point of the ramp,
all of the resulting energy was in the form of mechanical kinetic
energy.
Compare (the difference) the potential energy to the kinetic
energy. Using the above example, substitute and calculate the
mechanical energy due to frictional forces from your lab.
(PE) beginning of action –
___________ J
friction
_________ J
=
(KE) end of action
_________ J
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Summary Questions:
1. If the ramp height were doubled, what would be the new potential
energy? Show the E.S.A. in the box below.
1. According to step 6, friction caused a considerable loss of energy for the
cart and ramp system. Is the cart and ramp system an OPEN ENERGY
SYSTEM or a CLOSED ENERGY SYSTEM? Explain using data from your
lab.
2. Describe one design change for the cart which will decrease the loss of
energy due to friction. Use your own wording.
___________________________________________________________
___________________________________________________________
___________________________________________________________
___________________________________________________________
3. Describe why the design change will decrease the loss of energy due to
friction. Use your own wording.
___________________________________________________________
___________________________________________________________
___________________________________________________________
___________________________________________________________
4. Draw and label the design change from question 3 in the box below.
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Brainstorm Design Options:
Car Body:
 Shape
 Size
 Construction Materials
Wheels:
 Number of Wheels
 Diameter
 Width
 Composition(what materials make-up
the wheels)
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