Work, Power and Energy Review

Transcription

1 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.

2 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.

3 Work, Power and Energy Energy Conservation of Energy Work Power Potpourri Q $100 Q $200 Q $300 Q $400 Q $500 Q $100 Q $100 Q $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

4 $100 Question from Energy is the energy of an object in motion

5 $100 Answer from Energy Kinetic energy

6 $200 Question from Energy Pulling back a rubber band is a form of storing energy

7 $200 Answer from Energy Potential

8 $300 Question from Energy Energy is a measure of an object s

9 $300 Answer from Energy Ability to do work

10 $400 Question from Energy What is the kinetic energy of a 15 kg boulder resting at the top of a 12 m cliff?

11 $400 Answer from Energy 0 J (Not moving = no kinetic energy)

12 $500 Question from Energy What is the potential energy of a 15 kg boulder resting at the top of a 12 m cliff?

13 1764 J $500 Answer from Energy

14 $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.

15 $100 Answer from Conservation of Energy A. Its kinetic energy is mostly converted to potential energy.

16 $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!

17 $200 Answer from Conservation of Energy Use less or Don t convert energy into less useful forms, like heat.

18 $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?

19 $300 Answer from Conservation Heat (from friction) of Energy

20 $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?

21 $400 Answer from Conservation 2.5 J of Energy

22 $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?

23 $500 Answer from Conservation 14 m/s of Energy

24 $100 Question from Work Work is a measure of

25 $100 Answer from Work How much energy is transferred.

26 $200 Question from Work One unit for work is a Joule. A Joule is equivalent to a

27 $200 Answer from Work Newton-meter [N-m]

28 $300 Question from Work How much work is done if a 20 N force is used to slide a box 4 meters?

29 80 J $300 Answer from Work

30 $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?

31 $400 Answer from Work 0 J No movement means no work

32 $500 Question from Work How much work is done to lift a 4000 g barbell to a height of 2 m?

33 $500 Answer from Work 8 J 4000 g = 4 kg

34 Daily Double! You have 30 seconds to submit your wagers.

35 $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

36 $100 Answer from Power B. How many Joules are converted to other forms of energy (this is a definition of work)

37 $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.

38 $200 Answer from Power A student that runs. Same work, less time.

39 $300 Question from Power Calculate the power of a machine that can do 2400 J of work in 8 seconds.

40 300 W $300 Answer from Power

41 $400 Question from Power How much energy does a 1500 W microwave use if it is on for 40 seconds?

42 60,000 J $400 Answer from Power

43 $500 Question from Power How powerful is a weight lifter who lifts a 400N weight 2 m in 1.6 seconds?

44 500 W $500 Answer from Power

45 $100 Question from Potpourri Which force does the most work? How do you know?

46 C $100 Answer from Potpourri

47 $200 Question from Potpourri Work has the same units as what other quantity?

48 $200 Answer from Potpourri Energy

49 $300 Question from Potpourri Complete the sentence: Energy can never be created or destroyed, just

50 $300 Answer from Potpourri Energy can never be created or destroyed, just converted from one form to another.

51 $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?

52 $400 Answer from Potpourri Neither. Gravity accelerates all objects the same regardless of mass.

53 $500 Question from Potpourri An ice skater is gliding across the ice at a constant speed. Is she doing work?

54 $500 Answer from Potpourri No. No acceleration means no force. No force means no work.

55 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?

56 Final Jeopardy Answer The Calorie (= 4,187 Joules)