Group: __________________________
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Skateboard Physics Lab – Part 1 (1 of 3)
Vocabulary: Give a very brief description of the following terms.
 kinetic energy (KE): __________________________________________________________
 gravitational potential energy (PE): ______________________________________________
 thermal energy: _____________________________________________________________
 mechanical energy: __________________________________________________________
 conservation of energy: _______________________________________________________
1. As the skate park opens on your screen, observe the movements of the skater in the half pipe.
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Does the skater reach the same height on the opposite sides of the track? __________
Where does he move the fastest? _____________________________________________
What do the pause and step buttons do (under the skater screen)? __________________
What do the blue dots on the track allow you to do? ______________________
Grab a piece of track and add it to the exiting track. Manipulate the old and new sections to
become familiar with the construction techniques.
2. Turn on the energy Pie Chart, Energy vs. Position Graph, and Bar Graph. (You may need to
move things around a little to see everything.)
 On all three visual aids, what colors represent potential energy, kinetic energy, and total
energy? _____________________________________________________________
 On the Energy vs. Position Graph, what is the total energy of the skater? ___________J
 Where does the skater have the largest kinetic energy and the largest potential energy?
________________________________________________________________________
 It should be clear on the Energy-Position and Bar Graph that the Total Energy is really the
Mechanical Energy, which is the sum of the ___________ and ____________ energies.
3. Reset the simulation: Display the grid, potential energy reference, and the bar graph. The
potential energy (PE) reference level is at ground level. Move the PE reference while the skater is
moving and answer the following questions.
 As the PE reference level is moved, does the motion of the skater change? ________
 In the bar graph, what happens to the total energy as the PE reference level is
raised?_____________
 Raise the PE reference to get zero total energy.
o As the skater moves down the slope, is the PE positive or negative? ________
o As the skater moves down the slope, is the KE positive or negative? ________
 Using the Energy vs. Position Graph, what is the maximum KE of the skater? ________
o Does the KE part of the graph change as the PE reference changes? _______
o Does the maximum change in PE change as the PE reference is moved? _____
Skateboard Physics Lab – Part 1 (2 of 3)
Student A says that the location of the PE reference is critical because it changes the total
energy and total energy is important. Just look at the world. We need more energy.
Student B says that the location of the PE reference is a matter of convenience and can be
chosen anywhere to make calculations and understanding easier. It is the change in PE that
matters. Which student is correct? Explain?
4. Reset the simulation: Display the grid, PE reference, and Energy vs. Position box. Set the
skater on the ground. Set the gravity to 10 (for simplicity); open the edit skater box and set the
mass of the skater to 100 (for simplicity). Be aware that the bounciness and stickiness are related
to the skill of the skater and will not be altered now.
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Calculate the work to lift the skater to a height of 5 m. work = (force)(distance) = mgh =
_________ J.
 At the height of 5 meters, the reading on the Energy vs. Position box is ___________ J.
 Use the tape measure to find the distance from the PE reference to the bottom of the ramp.
This distance is ________ m.
 Place the skater on the ramp at the 5 m height. The skater now has a change in PE from the
top of his path to the bottom of his path. The PE is now __________ J.
o The maximum KE of the skater is now ______J.
Student A says the work done in raising the skater against gravity is equal to the change in
gravitational PE. Work done against gravity is the source of the potential energy. The maximum
KE of the skater is equal to the maximum change in PE as he skates the half pipe.
Student B says the skater has the same KE regardless of the PE level, so the work done has
nothing to do with the KE or PE. Student A is just playing with numbers.
Which student is correct? Explain.
5. Reset the simulation: Display the grid, PE reference, and Energy vs. Time box. Pause the
motion. Set the PE reference at the bottom of the half pipe. Run the motion for a short time and
pause the motion again.
 Examine the controls in the Energy vs. Time box. Briefly explore the functions of the following
controls: Rewind, Playback, Step, the grey bar:
 With the motion paused, move the friction bar from none to the middle of the scale. Push play
and observe the motion until the skater stops moving and pause the action.
o What is the red energy component? ___________
o What is the final value of the thermal energy? ______ KE? ________ PE? _______
o What is the final value of the total energy? _________ J
With the motion playing, push the ― Clear Heat button.
o Describe what happens to the various energy components.
Student X says that friction caused energy to be lost from the skater. In the end, the skater did
not have any energy. Energy was not conserved.
Student Y says agrees that mechanical energy was not conserved, but if thermal energy is
included then all of the energy is accounted for.
What do you think?
Skateboard Physics Lab – Part 1 (3 of 3)
6. Reset the simulation: Display the grid, PE reference, and energy box of your preference. From
the tracks option at the top of the display, select the Double Well track (not the roller-coaster
option). Remove the friction and place the skater at the 5 meter height and play the motion. With
the friction removed, the skater does not lose mechanical energy unless he jumps and lands. At
that point, he loses some energy. Set the skater at the five meter height and verify that he loses
mechanical energy on the jump. Then find the height from which he just makes it over the hump,
but does not lose energy.
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Describe the skater’s motion starting from 4.5 m.
 Describe the skater’s motion starting from 4 m.
 Describe the skater’s motion starting from 3.5 m.
7. Using the set up from 6 above, right click the track with your mouse and select the roller
coaster mode. Describe the behavior of the motion and energy with this track option.
8. Reset the simulation: Display the grid and PE reference. Locate the show path and clear
buttons in the green area to the right of the skater. When the skater is near the top of the left side,
push the show path button and then the stop button so that a series of purple dots is displayed.
Using the mouse click, one of these and display information. This information will disappear when
the dot is clicked again. Experiment with this feature with the PE reference line set at different
levels. Describe how this feature works and what information is displayed.
9. Reset the simulation: Load the loop track, select the
grid, PE reference, and Energy vs. Time graph. Stretch
the ends of the track above the 7 meter level. Describe
the motion for the following situations.
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Place the skater at the 6.5 meter level and release.
 Place the skater at the 6 meter level and release.
 Place skater at the 6 meter level with the track in
roller coaster mode and release.
Why does the skater needed to be moving relatively fast at the top of the loop in order to stay on
the track. Shouldn’t he have enough energy starting at the 6m level to make it through the loop?
Student A indicated that the simulation is faulty; as long as the student has enough energy to
reach that level, there should not be a problem.
Student B disagreed and remembered that for objects going around a circle, the centripetal
acceleration is given by v2/r and so there must be enough velocity to let g (the acceleration due
to gravity) be that acceleration.
Which student is correct?
Skateboard Physics Lab – Part 2
Create a roller coaster and provide an energy analysis of the motion
The purpose of this activity is to produce an exciting and fun roller coaster for the skater of your
choice, save the roller coaster for show, and to provide an energy analysis report of the
resulting motion. The analysis report should include an Energy vs. Time graph of a run and
comments correlating the analysis to the motion of the skater. The track and analysis must have
the features described below but may be more elaborate. The report will be a Word or
PowerPoint document.
Roller Coaster Project Rules
1. The roller coaster must contain at least one loop, one jump, and the skater must finish the run
on the screen on a designated section of track.
2. The analysis report must contain a picture of the track and the Energy vs. Time graph for a
run. You may stop the motion, copy the screen using the Alt-Ctrl-PrtScr key sequence, then
paste the image into the report document.
3. The analysis report must contain descriptions of energy transformations at various portions or
locations on the track. These energy transformations should be referenced to the corresponding
portions of the graph (one way this can be done is to label portions of the track and the graph).
Possible items to include in the analysis are:
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Potential energy to kinetic energy transformations
Thermal energy generating sources (friction and jumps)
Purpose of design characteristics (such as roller coaster track, friction level, starting level, etc.)
Other significant events or features of interest