Name _____________________________________________________________ DATE ___________________
Energy of a Rolling Ball Lab
Introduction
Raised objects have gravitational potential energy (PE).
Moving objects have kinetic energy (KE). The purpose of this lab is
to find out how these two kinds of energy are related in a system in
which a ball rolls down a ramp. There are nine stations. Your
teachers will assign you and your partner a starting station, and you
will be will be given 10 minutes to measure the height, distance
traveled, and time interval for a ball rolling down the ramp before
moving to the next station. You will also calculate the ball’s potential
energy at the top of the ramp, and its kinetic energy at the bottom
of the ramp. The rest of class time will be spent completing math
and analyzing the results to find the relationship between potential energy and kinetic energy.
Research
Define the following concepts:
Potential Energy: __________________________________________________________________________________
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Kinetic Energy: ____________________________________________________________________________________
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Gravity: ___________________________________________________________________________________________
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Gravitational Potential Energy: ____________________________________________________________________
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Law of Conservation of Energy: ___________________________________________________________________
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Give the formula for the following concepts, include units.
Speed:
Kinetic Energy:
Gravitational Potential Energy:
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Materials
scale
board, at least 90 cm (3 ft) long
box
ball
masking tape
meterstick
stopwatch
stack of books, at least 45 cm high
calculator
Hypothesis
The room is set up in 9 stations.
 Three of the stations are “height 1” and is the lowest height.
 Three stations are “height 2”, which is an intermediate height.
 Three stations are “height 3”, which is the tallest height.
With your partner, look at the different height stations. Based on your observations predict the
following:
Which station do you believe will have the highest potential energy? Lowest potential energy?
Why?
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Which station do you think will have the highest kinetic energy? Lowest kinetic energy? Why?
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Which station do you think will take the shortest amount of time for the ball to reach the bottom of
the ramp? The longest time? Why?
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Which station do you think will have the fastest speed? The slowest speed? Why?
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Procedure
1. Go to the assigned height station.
2. Weigh the ball in kilograms and record in data table I.
HINT: scales give you the weight in grams, you must
MOVE THE DECIMAL SPACE over to the left 3 spots in
order to convert to kilograms!
3. Using the meter stick, determine the height of the ramp by measuring from the table top to the
highest point on the ramp: Record the height in meters in the data table I.
HINT: If you measured the height of the ramp in centimeters you must convert this to meters.
You must move the decimal to the left 2 spots!
4. Again, using the meter stick, determine the length of the ramp. Do not include the “catch box”
into this measurement. Use the diagram as a reference. Record in data table I.
5. For trial 1, place the ball on the ramp at the tape. Use the stopwatch on your phone to measure
how long it takes IN SECONDS for the ball to reach the bottom of the ramp. LET THE BALL GO,
so that it rolls down the ramp. DO NOT PUSH IT. Record this
time in data table I.
6. Repeat step 5 twice more and record in data table I.
7. After the third trial, calculate the average travel time and
record in data table I.
HINT: add all travel times together and divided by three to find the average.
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Data Table I
Height 1
Mass of ball (kg)
Height of Ramp (m)
*****AT THE END OF 10 MINUTES,
Length of Ramp (m)
YOUR TEACHER WILL TELL YOU
TRIAL 1 Time (s)
TO MOVE STATIONS. IF YOU ARE
TRIAL 2 Time (s)
CONFUSED, ASK!!*****
TRIAL 3 Time (s)
AVERAGE Time (s)
(Time 1 + Time 2 + Time 3 / 3)
Data Table II
8. Repeat steps 3-7 for height 2
and record information in data
table II.
*****AT THE END OF 10 MINUTES,
YOUR TEACHER WILL TELL YOU
TO MOVE STATIONS. IF YOU ARE
CONFUSED, ASK!!*****
Height 2
Mass of ball (kg)
Height of Ramp (m)
Length of Ramp (m)
TRIAL 1 Time (s)
TRIAL 2 Time (s)
TRIAL 3 Time (s)
AVERAGE Time (s)
(Time 1 + Time 2 + Time 3 / 3)
Data Table III
Height 3
Mass of ball (kg)
9. Repeat steps 3-7 for height 3
and record information in data
table III.
Height of Ramp (m)
Length of Ramp (m)
TRIAL 1 Time (s)
TRIAL 2 Time (s)
TRIAL 3 Time (s)
AVERAGE Time (s)
(Time 1 + Time 2 + Time 3 / 3)
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Analysis
1. In the data table below, you will need to complete various calculations for each ramp height.
For all of the calculations, equations can be found in the data table.
Ramp Height 1
Ramp Height 2
Ramp Height 3
Average speed (m/s)
Length of ramp / average time
Final speed (m/s)
Final speed = average speed x 2
Kinetic Energy (J)
KE = ½ mv2
Initial Potential Energy (J)
PE = mgh
Initial PE – KE (J)
2. Look at the potential energy at the top of the ramp for each of the three ramp heights. For
each ramp height, is the ball’s initial potential energy at the top of the ramp greater than, less
than, or the same as the ball’s kinetic energy at the bottom of the ramp?
Ramp Height 1: ______________________________________________________
Ramp Height 2: ______________________________________________________
Ramp Height 3: ______________________________________________________
3. As the ramp height was raised, did the ball’s potential and kinetic energy increase, decrease, or
stay the same?
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4. If the experiment was done with a ramp at Height 1, but a heavier ball was used instead, what
would happen to the potential energy? What would happen to the kinetic energy?
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5. If the length of the ramp is increased, what happens to the average speed? Explain how this
effects the potential and kinetic energy.
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Conclusion
1. Suppose that you perform this experiment and find that the values for kinetic energy are always
just a little less than the values for potential energy. Did you do the experiment wrong?
All of the potential energy should be converted to kinetic energy. What happened to the rest of
the potential energy?
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