Work, Power and Energy

Review

• Each table will work as a team to earn points by answering questions.

• There will be 25 seconds to answer each question.

• Answers, with formula when needed will be recorded on the whiteboards at each team table. Each team can use 2 calculators.

• Person writing rotates after each question.

• 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 or Jolly Rancher.

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 $200

Q $300

Q $400

Q $500

Q $100 Q $100Q $100 Q $100

Q $200 Q $200 Q $200 Q $200

Q $300 Q $300 Q $300 Q $300

Q $400 Q $400 Q $400 Q $400

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

_________________

$300 Answer from Energy

• Ability to do work

$400 Question from Energy

• What is the kinetic energy of a 15 kg

boulder resting 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

• 1764 J

$100 Question from

Conservation of Energy

• When a ball is thrown directly upward,

which of the following is true? How do you

know?

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

• If energy can be neither created nor

destroyed, what do we mean when we say

“Don’t waste energy!”

$200 Answer from Conservation

of Energy

• Use less or Don’t convert energy into less

useful forms, like heat.

$300 Question from

Conservation of Energy

• When a car rolls down a hill, most of its

potential energy converts to kinetic energy.

Where does most of the rest of it go?

$300 Answer from Conservation

of Energy

• Heat (from friction)

$400 Question from

Conservation of Energy

• An object starting with 20 J of potential

energy rolls down a hill. At the bottom, 7/8

of the potential energy has been converted

to kinetic energy. How much energy (in

Joules) was “lost” due to friction?

$400 Answer from Conservation

of Energy

• 2.5 J

$500 Question from

Conservation of Energy

• A 2 kg object sits at the top of a 10 m hill.

How fast will it be rolling at the bottom of

the hill?

$500 Answer from Conservation

of Energy

• 14 m/s

$100 Question from Work

• Work is a measure of _____________

$100 Answer from Work

• How much energy is transferred.

$200 Question from Work

• One unit for work is a Joule. A Joule is

equivalent to a _______________

$200 Answer from Work

• Newton-meter [N-m]

$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.

Schannerman pushes against a boulder with

200 N of force for 5 seconds but the boulder

doesn’t move?

$400 Answer from Work

• 0 J No movement means no work

$500 Question from Work

• How much work is done to lift a 4000 g

barbell to a height of 2 m?

$500 Answer from Work

• 8 J

• 4000 g = 4 kg

Daily Double!

• You have 30 seconds to submit your

wagers.

$100 Question from Power

• Which of the following is not a definition of

power? How do you know?

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 uses more power, 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 energy does a 1500 W

microwave use if it is on for 40 seconds?

$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?

$500 Answer from Power

• 500 W

$100 Question from Potpourri

• Which force does the most work?

How do you know?

$100 Answer from Potpourri

• C

$200 Question from Potpourri

• Work has the same units as what other

quantity?

$200 Answer from Potpourri

• Energy

$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. Assuming energy is conserved,

which car, if either, will be rolling faster at

the bottom of the hill?

$400 Answer from Potpourri

• Neither. Gravity accelerates all objects the

same regardless of 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:

• Like all objects, humans need energy to

cause change. What unit do humans most

often use to describe their own changes in

energy?

Final Jeopardy Answer

• The Calorie (= 4,187 Joules)