Name __________________________________________ Date _______________ Per ______
Energy and the Roller Coaster
Purpose:
To calculate the kinetic and potential energy of a marble along a roller coaster track. To discover
how mass, velocity and height affect kinetic and potential energy. To discover if energy is
conserved.
Hypothesis
Write an “If….then….” statement about how you think mass, velocity and height will affect kinetic
and potential energy of the marble as it moves down the track.
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Materials:
Roller Coaster kit
CPO timers
Meter stick
Triple Beam Balance
Procedure:
Part one: Position of Marble vs. Speed of Marble
1. Attach the roller coaster to the fifth hole on the physics stand pole.
2. When attaching the photogates to the roller coaster, be sure that the bottom of the photogate
is flat against the bottom of the track. If the photogate is not attached to the track properly,
the light beam will not cross the center of the marble and your calculated speed will not be
correct.
3. Connect the photogate to input A of the timer, and set the timer to interval mode.
4. Place the photogate at the 5 cm mark.
5. Measure the height of the photogate from the table to the center of the hole for the light
beam in meters and record.
6. Release the marble at the top of the ramp and record the time it took the marble to cross the
light beam in the data table.
7. The distance the marble travels is equal to its diameter. The diameter of the marble is
0.0019m.
8. The velocity of the marble is its diameter divided by the time from photogate A. Use your
data to calculate the velocity of the marble and record in data table 1.
9. Repeat steps 4 – 7 moving the photogate to the corresponding cm marks on your data table.
10. Repeat steps 4-9 with the black plastic marble.
Part two: Potential and Kinetic Energy
11. Potential Energy is the mechanical energy of position. In other words, potential energy is
how much potential something has to do work.
12. Use the triple beam balance to find the masses of the two marbles in grams. Convert the
mass into kilograms and record in data table 2.
13. Copy your data for the height from data table 1 into data table 2.
14. The formula used to measure P.E. is: Mass x Acceleration of Gravity (9.8) x Height
15. Calculate the Potential Energy of each marble at each position and record.
Part three: Kinetic energy
16. Kinetic Energy is the mechanical energy of motion. In other words, kinetic energy is how
much work an object is currently doing.
17. The formula for determining K.E. is: ½ (m x v2)
18. Copy your data for the velocity of the marbles from data table 1 into data table 3.
19. Copy your data for the mass of the marbles from data table 2 into data table 3.
20. Calculate the Kinetic Energy of each marble at each position and record.
Part four: Total energy
21. The total energy at each position on the roller coaster is calculated by adding the potential
and kinetic energies at each position.
22. Copy the potential and kinetic energies of the marbles from data tables 2 and 3 into data
table 4.
23. Find the total energy of each marble at each position and record in data table 4.
Analysis:
1. How does height off the ground affect the amount of potential energy the marble has?
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2. How would the potential energy of an object be different on the moon? Explain.
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3. How does height off the ground affect the amount of kinetic energy the marble has?
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4. How does the velocity at which an object is traveling affect the amount of kinetic energy the
marble has?
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5. The total energy you calculated in data table 4 should have been the same for each position.
Was this the case for your data? Explain why.
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Conclusion
The conclusion section needs to have five sentences:
1st sentence: Repeat the objective
2nd sentence: Tell how you achieved the purpose.
3rd sentence: State your hypothesis and explain if it was it correct or not and why.
4th sentence: Share what you learned.
5th sentence: This is a general summary of the lab. It ties into the first sentence of the purpose.
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Data Table 1
Photogate Height Time of Time of Distance Velocity of Velocity of
Placement (m) Steel Plastic Traveled by Steel Marble Plastic Marble
Marble (sec) Marble (sec) marble (m) (m/sec) (m/sec)
5 cm
25 cm
45 cm
60 cm
85 cm
105 cm
125 cm
Data Table 2
Photogate Height(m) Mass of Mass of Potential Energy Potential Energy
Placement Steel Marble Plastic of Steel Marble (J) of Plastic
(kg) Marble (kg) Marble (J)
5 cm
25 cm
45 cm
60 cm
85 cm
105 cm
125 cm
Data Table 3
Photogate Mass of Mass of Velocity of Velocity of Kinetic Kinetic
Placement Steel Plastic Steel Plastic Energy of Energy of
Marble(kg) Marble Marble Marble Steel Plastic
(kg) (m/sec) (m/sec) Marble (J) Marble (J)
5 cm
25 cm
45 cm
60 cm
85 cm
105 cm
125 cm
Data Table 4
Photogate Potential Potential Kinetic Kinetic Total Total
Placement Energy of Energy of Energy of Energy of Energy of Energy of
Steel Plastic Steel Plastic Steel Plastic
Marble (J) Marble (J) Marble (J) Marble (J) Marble (J) Marble (J)
5 cm
25 cm
45 cm
60 cm
85 cm
105 cm
125 cm