Theme: Skateboard Science
Title: Some Physics of Skateboard Riding
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Overview: Riding a skateboard requires some level of
skill. Physical science tells us that these skills needed
are mastery of one’s center of gravity, overcoming
friction and (briefly) conquering gravity. Implied in this is
the necessary transfer of energy and power input.
Skateboarders try to maximize momentum, power, and
balance. Of course, as you can well imagine, maximizing these physical
principles also maximizes another factor – risk.
Grade Level: 9-12
Subject Matter: Physics
Duration: 2, 50-minute lessons
National Standards Addressed:
Physical Science: Content Standard B
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Motion and Forces
Conservation of energy and increase in disorder
 Interaction of energy and matter
Objectives:
By the end of the lesson, the students will be able to:

Describe the following physical phenomenon: center of gravity,
acceleration, velocity, impulse, and momentum.
 Apply the above principles to sports, like riding a skateboard.
Materials:
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Skateboard (or equivalent)
Whiteboard and markers
Computers
Internet
Projector
Procedure:
1. Hook
a. Take out a ten dollar bill.
b. Ask the class if anyone would like to have it. They will probably say
yes.
c. Then, tell them that all they have to do is pick it up off the floor.
d. Have the students stand with their backs to the wall, with the heels
of their feet up against the wall.
e. Place the money about 7 inches away from their toes.
f. Tell them to pick it up. It’s is almost impossible to pick up the
money. They will almost fall over trying to get it.
g. Let everyone try.
h. Summarize with the activity discussing center of gravity.
2. Physics of Riding a Skateboard
a. Center of Gravity
i. Define Center of Gravity: The center of gravity of a
collection of masses is the point where all the weight of the
object can be considered to be concentrated or,
ii. the point at which the entire weight of a body may be
considered as concentrated so that if supported at this point
the body would remain in equilibrium in any position
iii. Show the students the following wine bottle souvenir:
http://www.matchlessmasterpiece.com/decorativewinebottle
holder.php
1. Explain how it works – the bottle is resting over its
center of gravity.
2. If time permits, try making one:
http://www.wineintro.com/products/racks/balance.html
iv. Do the following activities and discuss the results and the
implications of keeping your center of gravity:
http://www.csr.utexas.edu/grace/education/activities/pdf/Fun
_Gravity.pdf
v. Finish this section with a whiteboard activity.
1. Ask the students to describe how and what a
skateboarder will do to keep his/her center of gravity.
2. Have the students work in groups of three (or so) and
have them write their explanations on whiteboards.
3. Have the students present their responses to the
class.
b. Gravity, Velocity, Acceleration and Skating
i. Show the following clip of Jake Brown’s pulling of a “720”
and the falling from over 40 feet to the ground. Note: this
was real in the 2007 X Games. Jake walked away,
sustaining injuries. Jake was released from the hospital
after three days!! See it here:
http://www.metacafe.com/watch/751874/jake_brown_live_cr
ash/
ii. After viewing the clip have the students answer the
questions on the handout entitled: Gravity, Velocity,
Acceleration, and Skating”
iii. Review answers with the students.
iv. If there is time (and the right conditions), try the following.
1. Use the idea of a ball rolling down an inclined plane
but switch the ball out with a student on a skateboard.
2. Distances could be marked with a chalk line.
Students could stand at the designated distances with
a stopwatch to record the time.
3. Sample lab:
www.tvgreen.com/Spectrum08/document/MotionLab.
doc
c. Momentum, Impulse, and the Ollie
i. Present the following information on momentum to the
students. This can be your choice. A short PowerPoint
presentation would work well.
1. What is momentum:
a. It refers to moving things.
b. It is the product of the objects mass times its
velocity: p = m ∙ v
2. How to increase momentum:
a. Use a more massive object.
i. A semi truck has more momentum than
a Volkswagen Beetle.
b. Increase the velocity of the object.
i. A car moving at 15 m/s has more
momentum than an identical car (with
identical mass) moving at 10 m/s.
c. Increase both the mass and velocity of the
object.
i. This can be done by picking up two of
your friends (increase in mass) and
driving faster than you did to get to their
houses (increase speed)
3. Decrease the momentum
a. Do the opposite of the previous listed items.
i. Decrease the mass.
ii. Decrease the velocity.
iii. Decrease both.
4. Changing momentum = Impulse
a. Impulse is the product of force (F) times time
(t).
b. A huge force applied over a short time could be
equal to a small force being applied over a long
time.
5. Power
a. Work is equal to force times distance.
b. Power is Work divided by time
ii. Listen to Pulse of the Planet program 4362 Skateboard Ollie. Then, watch the video at:
http://video.about.com/skateboard/How-to-Ollie.htm
1. At some point in this portion of the lesson have a
student demonstrate an Ollie.
2. Discuss the implications of momentum and impulse.
iii. Handout the assignment: “Momentum, Impulse, and the
Ollie.” Describe the assignment and when it is due.
d. Conservation of Energy / Energy Transfer
i. Ask students to define “Conservation of Energy”
ii. Extend the principle by discussing how energy is transferred
from the sun (solar energy) to green plants which make food
(chemical energy) which we eat and digest (chemical
energy) and use to move (kinetic energy).
iii. Using the whiteboards, have the students show energy
transfer/law of conservation of energy to perform an “Ollie.”
iv. Students are to present answers to the class.
v. Troubleshoot answers and probe each group for deeper
understanding.
Handouts:
Gravity, Velocity, Acceleration, and Skating
Answer the following questions using your textbook, and the
listed websites.
1. What is Jake Browns weight: _______lbs.
http://www.mahalo.com/Jake_Brown
2. Convert this weight to mass: _________ kg
3. Define gravity:
4. Define velocity:
5. Define acceleration:
6. Define acceleration due to gravity:
7. Using the video, measure Jake Brown’s time of free fall (when
he lost his balance): _______ sec.
8. Using the equation: a = vf-vi/t, find out Jake’s velocity right
before impact (vf). Your answers from #6 and #7 will help you.
9. Find out the force that Jake had when he hit the ground. Use
the equation: F = ma. Your answer from #2 and #6 will help
you.
10. If you were to graph the distance Jake went over time, what
would it look like?
11. What physical phenomenon is question 10 referring to?
12. If you were to graph Jake’s velocity every .25 sec, what
would the graph look like?
13. What physical phenomenon is question 12 referring to?
14. What would Jake have to do to not fall back to earth? (hint:
escape velocity)
15. In all, what force acts to oppose all motion?
Momentum, Impulse, and the Ollie
Directions: Use the information you just learned on momentum
and Impulse to describe how a skateboarder could obtain the
highest Ollie possible. Keep in mind the following items:
 The skaters weight (mass)
 The skateboards mass
 The strength of the skater
 The speed
 The strength of the force
 The duration of the force
 The amount of power needed
 Friction’s role
You may use drawings, data tables, writing etc. to complete this
task.
Use the space below for your description.
Additional Resources
Web Sites
Forces of the Ollie – Skateboard Science / Exploratorium.edu
http://www.exploratorium.edu/skateboarding/trick02.html
What is Acceleration? (PDF) – Rutgers University
http://www.rci.rutgers.edu/~dougproj/programs/outreach/ForcesMotion/accelaration.pdf
Acceleration – Scienceclarified.com
http://www.scienceclarified.com/A-Al/Acceleration.html
Position, Velocity and Acceleration – University of Tennessee
http://electron9.phys.utk.edu/phys135d/modules/m1/m1ex1.htm
Center of Gravity – NASA
http://www.grc.nasa.gov/WWW/K-12/airplane/cg.html
How to Calculate Center of Gravity – WikiHow
http://www.wikihow.com/Calculate-Center-of-Gravity
Sir Isaac Newton: The Universal Law of Gravitation - University of Tennessee
http://csep10.phys.utk.edu/astr161/lect/history/newtongrav.html
Momentum – Glenbrook High School
http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/momentum/u4l1a.html
Momentum – Physics247.com
http://www.physics247.com/physics-help/momentum.shtml
Other
Center of Gravity Experiment – Union College / American Chemical Society/American
Institute of Physics
http://www.kids.union.edu/fsnCenterOfGravity.htm
Lessons on Momentum – Science Joy Wagon
http://www.sciencejoywagon.com/physicszone/06momentum/
Jumping with Energy Lesson (flic flac activity) – Science.org
http://www.science.org.au/pi/book6/t6l2.pdf
Special thanks to the following scientists for their help with this
project:
Pulse of the Planet Program: #4362 Skateboard -Ollie
Paul Schmitt
Founder, CreateAskate.org
Header Image
Name: Parabola
Credit: Wikimedia Commons