Work, Power and Energy
Review
• Each table will work as a team to earn points by answering
questions.
• There will be 60 seconds to answer each question from the time
I am done reading unless otherwise noted.
• Answers will be recorded and presented on the whiteboards at
each team table.
• Correct answers will earn the points denoted by the question.
Incorrect answers will not be penalized.
• The choice of category and question will rotate among teams.
• At Final Jeopardy, each time may wager all of their earned
points, or $1000, whichever is greater.
• The winning team will earn 1 point of extra credit each on
tomorrow’s test.
Strategy
• Work together with your team.
• Talk quietly but discuss possible options.
Make sure to write down your solution
before time runs out.
• After each question and answer we will
have time to discuss and answer questions.
Work, Power and Energy
Energy
Conservation
of Energy
Work
Power
Potpourri
Q $100
Q $100
Q $100
Q $100
Q $100
Q $200
Q $200
Q $200
Q $200
Q $200
Q $300
Q $300
Q $300
Q $300
Q $300
Q $400
Q $400
Q $400
Q $400
Q $400
Q $500
Q $500
Q $500
Q $500
Q $500
Final Jeopardy: Units
$100 Question from Energy
• ___________ is the energy of an object in
motion
$100 Answer from Energy
• Kinetic energy
$200 Question from Energy
• Pulling back a rubber band is a form of
storing __________ energy
$200 Answer from Energy
• Potential
$300 Question from Energy
• Energy is a measure of an object’s
_________________
(give the definition of energy from your
notes!)
$300 Answer from Energy
• Ability to do work
$400 Question from Energy
• What is the kinetic energy of a 15 kg
boulder at rest at the top of a 12 m cliff?
$400 Answer from Energy
• 0 J (Not moving = no kinetic energy)
$500 Question from Energy
• What is the potential energy of a 15 kg
boulder resting at the top of a 12 m cliff?
$500 Answer from Energy
• 1800 J
$100 Question from
Conservation of Energy
• When a ball is thrown directly upward,
which of the following is true?
A. Its kinetic energy is mostly converted to
potential energy.
B. Its potential energy is mostly converted to
kinetic energy.
C. Its kinetic energy is mostly converted to heat.
$100 Answer from Conservation
of Energy
• A. Its kinetic energy is mostly converted to
potential energy.
$200 Question from
Conservation of Energy
• The Law that energy can be neither created
nor destroyed, is known as the…
$200 Answer from Conservation
of Energy
• Law of Conservation of Energy.
$300 Question from
Conservation of Energy
• When a car rolls down a hill, most of its
potential energy converts to kinetic energy,
but not all of it. Some energy is “lost.”
Where does most of the rest of it go?
(Hint: wheels rolling on road have friction…)
$300 Answer from Conservation
of Energy
• Heat (from friction)
$400 Question from
Conservation of Energy
• A 2 kg object sits at the top of a 10 m hill.
How much kinetic energy will the object
have at the very bottom of the hill when it is
rolling its fastest?
(Hint: all P.E. will convert into K.E.)
$400 Answer from Conservation
of Energy
• 200J
Energy is conserved, so 200J of PE at top of
hill become 200J of KE at bottom of hill
$500 Question from
Conservation of Energy
• An object starting with 20 J of potential
energy rolls down a hill. At the bottom, 18J
of the potential energy has been converted
to kinetic energy. How much energy (in
Joules) was “lost” due to friction?
$500 Answer from Conservation
of Energy
• 2J
$100 Question from Work
• Work is a measure of _____________
(definiton from your notes)
$100 Answer from Work
• How much energy is transferred.
$200 Question from Work
• One unit for work is a Joule. A Joule is also
the unit used for_______________
$200 Answer from Work
• Energy
$300 Question from Work
• How much work is done if a 20 N force is
used to slide a box 4 meters?
$300 Answer from Work
• 80 J
$400 Question from Work
• How much work is done if Mr. Richter
pushes against a boulder with 200 N of
force for 5 seconds but the boulder doesn’t
move?
$400 Answer from Work
• 0J
$500 Question from Work
• How much work is done to lift a 40 kg
barbell to a height of 2 m?
(Hint: need to know the force to lift the
barbell, so find the weight of the barbell)
$500 Answer from Work
• 800 J
Daily Double!
• You have 30 seconds to submit your
wagers.
$100 Question from Power
• Which of the following is not a definition of
power?
A. The rate of energy transfer
B. How many Joules are converted to other
forms of energy
C. The rate at which work is done
D. How quickly energy is converted
$100 Answer from Power
• B. How many Joules are converted to other
forms of energy (this is a definition of
work)
$200 Question from Power
• Which is more powerful, a student that runs
up the stairs or a student that walks?
Assume they have equal mass.
$200 Answer from Power
• A student that runs. Same work, less time.
$300 Question from Power
• Calculate the power of a machine that can
do 2400 J of work in 8 seconds.
$300 Answer from Power
• 300 W
$400 Question from Power
• How much work does a 1500 W microwave
do if it is on for 40 seconds?
(Hint: rearrange power equation to solve for
work. Set up a formula triangle)
$400 Answer from Power
• 60,000 J
$500 Question from Power
• How powerful is a weight lifter who lifts a
400N weight 2 m in 1.6 seconds?
(Hint: remember, in order to find power, you
must first know how much work is done!)
$500 Answer from Power
• 500 W
$100 Question from Potpourri
• Which force does the most work?
$100 Answer from Potpourri
• C
The force is in same direction as the
movement
$200 Question from Potpourri
• What are the units for Power?
$200 Answer from Potpourri
• Watts
$300 Question from Potpourri
• Complete the sentence:
Energy can never be created or destroyed, just
__________
$300 Answer from Potpourri
• Energy can never be created or destroyed,
just converted from one form to another.
$400 Question from Potpourri
• A 1000 kg car and an 1200 kg car roll down
a hill. If both cars have the same speed,
which would have more kinetic energy?
Why?
$400 Answer from Potpourri
• 1200kg car since it has more mass.
$500 Question from Potpourri
• An ice skater is gliding across the ice at a
constant speed. Is she doing work?
$500 Answer from Potpourri
• No. No acceleration means no force. No
force means no work.
Final Jeopardy:
1. At which point would the cart have the
most P.E.? Why?
2. At which point would the cart have the
most K.E.? Why?
Final Jeopardy Answer
1. Point A because it’s at the highest (PE = mgh)
2. Point C because it’s at the bottom of the hill and
all P.E. would have become K.E., making the cart
have a high speed