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Science of NHL Hockey: Work, Energy & Power
Subject Area: Physics
Grade Level: 9–12 (Physics)
Lesson Title: Work, Energy & Power
National Science Education Standards:
 Science as Inquiry: 9–12
 Motions and Forces: 9–12
 Conservation of Energy and Increase in Disorder: 9–12
 Interactions of Energy and Matter: 9–12
Suggested Prior Knowledge: concepts of mass, force, time, and distance; lab techniques of
measuring mass, time, force, and distance. Note that students might more easily grasp the
concepts in this video if they have already viewed the videos Newton’s Three Laws of Motion
and Force, Impulse & Collisions.
Purpose and Introduction: This video uses the hockey technique of a slap shot to demonstrate
the concepts of work, energy, and power. The potential and kinetic energy involved in the action
are highlighted. The activity will allow students to explore examples of work, potential and
kinetic energy, and power, and to demonstrate the conservation of energy.
Key Vocabulary:
energy—the ability to do work.
force–an influence on an object that causes a change in velocity or shape.
kinetic energy—energy of motion.
law of conservation of energy—energy can be neither created nor destroyed.
potential energy—energy that is stored.
power—the rate at which work is done.
work—the result of a force acting on an object that causes the object to move; the product of
a force and the distance it moves an object.
Objectives:
1. Students will understand the relationships between work, energy, and power.
2. Students will design and carry out an investigation to measure the power output of the
human body.
3. Students will demonstrate conservation of energy through the conversion of potential
energy of a spring to kinetic energy.
Materials:
- meter stick
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- stopwatch
- scale (100 kg capacity)
- ring stand
- standard mass
- spring (with small mass)
- string
Procedure:
1. Use the video to review with students the basic concepts of work, energy, power, and
conservation of energy. Elicit from students that kinetic energy is the energy of a moving
body, such as a moving hockey puck. Students should also be able to use examples from the
video to describe the law of conservation of energy, which tells us that kinetic energy is not
created from nothing but is instead produced by converting other forms of energy (such as
the potential energy stored in a hockey stick). Ensure students do not equate energy with
power based on the video definition of energy (the power that will propel the puck into
action). Reinforce that energy is the ability to do work and that power is the rate at which
work is done. Also point out to students that the onscreen graphics at about the 4 minutes
mark are illustrative only and not scientifically accurate. As the stick is scraping the 1 ft
across the ice, it has not yet struck the hockey puck. In fact, work would be calculated using
the distance that the force (stick) is in actual contact with the puck, which could be 1 ft, or
perhaps more or less.
To encourage discussion, ask students to give examples from hockey or other sports as they
answer the following questions, using appropriate units of measure.
 What are the units of force?
 How are force and work related?
 How is power different from work?
 What is the difference between potential energy and kinetic energy?
2. Lab protocols should be followed, incorporating safety equipment. Goggles must be worn at
all times.
3. Guide students to design investigations that will allow them to measure power output and the
conversion of potential to kinetic energy. Explain that the work done climbing a flight of
stairs gives a person gravitational potential energy and a stretched spring also has potential
energy (like a hockey stick that flexes). Discuss with students how the potential energy of the
spring is converted to kinetic energy when a suspended mass oscillates up and down on the
spring. While students might design other valid investigations, those described in this lesson
are examples. Questions such as the following can help focus students’ plans and guide them:
 What do you need to know to measure work?
 What do you need to know to measure the power that produced a given amount of work?
 How do you measure potential energy?
 How do you measure the speed of a mass on a spring?
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Power
4. One way students can easily measure power output is to form small groups and gather at a
flight of stairs. One student runs up a flight of stairs from a standing start. Other members of
the group record the height of the stairs, the mass of the runner, and the time the runner needs
to climb the stairs. The total energy output is equal to the mass of the runner times g
(acceleration due to gravity) times the height of the staircase. Power is total energy output
divided by the time needed to run up the stairs, which will be a few hundred joules per
second (a fraction of a kilowatt).
Conservation of Energy
Like someone at the top of a staircase, a stretched spring has potential energy. Students could
follow steps similar to these to explore how energy is conserved.
5. As a first step in determining the potential energy, each group of students ties the upper end
of a spring to a ring stand and marks the position of its lower end. The students then tie the
mass onto the lower end and mark its equilibrium position. The spring constant is obtained
by solving the equation mg = kx, where m is the mass of the suspended mass, g is the
acceleration due to gravity, k is the spring constant, and x is distance the spring is stretched.
6. To add potential energy to the spring, students could pull the mass downward to stretch the
spring a measured distance x. The potential energy stored in the stretched spring is PE =
2
1
2 kx .
7. Next, students release the mass and measure the time it takes to complete 10 or more cycles
from bottom to top and then back. Students divide the distance the oscillating mass travels
during one cycle by the time needed for one cycle to find the average speed of the mass, vav .
(The distance it travels in one cycle is four times the distance the spring is stretched from its
equilibrium position.)
8. The speed measured in Step 7 is the average speed of the oscillating mass, but to show
conservation of energy, students need the maximum speed of the mass. Maximum speed is
directly proportional to average speed: vmax = 2 vav . From the maximum speed, students
calculate the maximum kinetic energy of the mass, KE =
1
2
2
mvmax
.
9. Because energy is neither created nor destroyed, the total energy of the mass and spring
should remain constant. Potential energy is greatest when the spring is longest and the mass
is stationary at its lowest point. That energy is entirely converted to kinetic energy when the
mass is in the middle of its cycle and moving at its maximum speed. So, allowing for
2
measurement errors in time and distance, students should find that 12 kx 2 = 12 mvmax
. Discuss
with students where errors could have occurred if their calculations do not agree.
10. To follow up on this investigation, have students investigate wind power and answer
questions such as the following:
 How is the kinetic energy of wind converted to electric power? How does power
available depend on wind velocity?
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
How does the power available from a large wind turbine compare to the amount of
power a student’s muscles can produce climbing a flight of stairs? How does it compare
to the 7700 joules/second a hockey player’s slap shot can produce?
Additional Resources:
 http://www.teachengineering.org/view_activity.php?url=http://www.teachengineering.or
g/collection/cub_/activities/cub_energy/cub_energy_lesson01_activity1.xml
 http://www.4physics.com/phy_demo/HookesLaw/HookesLawLab.html
 http://windeis.anl.gov/guide/basics/index.cfm
 http://www.altoonamirror.com/page/content.detail/id/553674/Pumped-storage-systemhelps-handle-power-demand.html
 http://www.technologystudent.com/energy1/pstr1.htm
 http://bankhead.highline.edu/class/phys100/5_Labs/Lab07/Lab07.pdf
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Student Worksheet for Work, Energy & Power
Experiment Title: _____________________________Date: __________Name: _____________
Student Hypothesis: _____________________________________________________________
Materials: _____________________________________________________________________
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Procedure:
Wear safety goggles for all lab work.
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Data and Observations:
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Analysis of Data: _______________________________________________________________
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Conclusion: ___________________________________________________________________
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