Conservation of Energy
Teacher’s Guide
by: Chase Taylor (Shoban HS)
Lesson Overview: Conservation of Energy Principles
Subject area(s): Physics and
Engineering
Topic: Conservation of momentum
National Science Education Standards Addressed:
1. List them here
Audience: Highschool
Resources:
1. http://en.wikipedia.org/wiki/Right_hand_rule
2. http://en.wikipedia.org/wiki/Cross_product
3. Know your material – Any physics book.
Suggested time: 40 minutes
1. Time can be adjusted as
needed.
Materials:
 “Zecar” flywheel toy car
 “Frictionless seat” (Chair with
ball bearing joints)
 Bicycle wheel.
Learning Objectives:
Students will:
1. Learn and understand Newton’s 2nd law (force) and its applications. Equations to be
memorized are:
a. Force: F=ma
b. Momentum: L=mv
c. Conservation of Linear Momentum: L1= L2 --> m1vv1= m2v2
d. Inertia = resistance to acceleration (formulas vary by geometry).
e. The “Right-Hand Rule.”
Background:
1. Not only can the students understand what forces area and that energy is conserved, but they
can feel it act on them.
2. The ice skater spin.
a. Angular momentum is conserved when the ice skater pulls their arms in and they spin
faster as a result.
3. Energy can be stored as angular momentum.
a. The flywheel in the Zecar stores the initial push and takes advantage of the gear ratio,
inertia, and angular momentum to keep the car moving for extended distances.
4. Bicycle wheel as a gyroscope.
a. Angular momentum is conserved in the wheel
b. When spinning, the wheel resists acceleration (inertia).
c. If you push against the wheel, it pushes back at you (Newton’s first law).
d. As you push the wheel it turns you (conservation of angular momentum).
5. Two forces “crossed“obey the right-hand rule.
Idaho State University’s GK-12 Project
http://www.isu.edu/departments/gradk12/index.html
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a. The direction of the angular momentum produced is governed by the right-hand rule.
(Curve your right-hand fingers in the direction of spin and your thumb points in the
direction the angular momentum is directed).
b. Gravity is a force acting on the angular momentum.
c. Hang a spinning gyroscope by one axis and it will not fall as expected. Instead the
gyroscope spins about the point by which it is hung. This is due to the “cross product”
of the angular momentum and gravity.
Assessment Strategy:
1. Ask the kids why the spinning wheel is hard to turn. (Inertia- resistance to acceleration)
2. Using the right-hand rule, have the kids predict which direction the hanging gyroscope will
spin.
3. With each principle you can ask the students how it applies to real life situations.
Teaching Tips:
This is the place to offer suggestions and highlight potential problems. Depending on the lesson this could be
written a variety of ways.
One way:
Obtaining Materials and Experiment prep: Most physics teachers will have a bicycle wheel to use for this demo.
Zecar is found on the internet for purchase (ie: http://www.randomaccents.com/kl1589.html).
Engage – Ask the student who has ever wanted to be an ice skater. What does every ice skater do at the end of
their performance? This is especially fun if the class is comprised mostly with boys!
Explore – Hand one of the kids the spinning bicycle wheel and ask them why it is so hard to handle. Before
hanging the gyroscope ask the students what they think will result once you let go. This surprises them.
Explain – Watch the reaction of the kids when explaining a specific physical law to see if they are
understanding it. It was useful to tell them in advance that I was going to explain a law and then a formula.
Extension(s):
What instruments or daily things make use of angular momentum, etc.? Bicycles, airplane navigation
instruments, Segway self balancing scooter (http://www.segway.com/), etc..
References:
Give credit where credit is due.
This material was developed with support from the National Science Foundation’s Graduate Teaching Fellows in K-12 Education (GK-12) program
(DGE-0338184) and Idaho State University. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the
author(s) and do not necessarily reflect the views of the NSF.
FINALLY – attach as separate files any student worksheets or overheads/powerpoints - I will link them to
this document in the resources section.
Please place the above disclaimer at the bottom of any student handouts that you attach. THANKS!
Idaho State University’s GK-12 Project
http://www.isu.edu/departments/gradk12/index.html
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