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Chapter 4 Sections 1 & 2

Chapter 4 Sections 1 & 2. Work, Power and Machines. 1. What is work?. A. The type of energy that a moving object has B. The rate at which work is done or energy is transformed C. The unit used to express power

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Chapter 4 Sections 1 & 2

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  1. Chapter 4 Sections 1 & 2 Work, Power and Machines

  2. 1. What is work? • A. The type of energy that a moving object has • B. The rate at which work is done or energy is transformed • C. The unit used to express power • D. The transfer of energy using a force that causes an object to move in the direction of the force

  3. ANSWER: • Work is… • D. The transfer of energy using a force that causes an object to move in the direction of the force

  4. 2. What is power? • A. The type of energy that a moving object has • B. The rate at which work is done or energy is transformed • C. The unit used to express power • D. The transfer of energy using a force that causes an object to move in the direction of the force

  5. ANSWER • Power is… • B. The rate at which work is done or energy is transformed

  6. 3. What is kinetic energy? • A. The type of energy that a moving object has • B. The rate at which work is done or energy is transformed • C. The unit used to express power • D. The transfer of energy using a force that causes an object to move in the direction of the force

  7. ANSWER • Kinetic energy is … • A. The type of energy that a moving object has

  8. 4. What is a machine? • A. The type of energy that a moving object has • B. The rate at which work is done or energy is transformed • C. A device that helps do work by either overcoming a force or changing the direction of the force • D. The transfer of energy using a force that causes an object to move in the direction of the force

  9. ANSWER • A machine is… • C. A device that helps do work by either overcoming a force or changing the direction of the force

  10. 5. What is work input? • A. A number that tells how many times a machine multiplies a force • B. A quantity, usually expressed as a percentage, that measures the ratio of work output to work input • C. The work done ON a machine • D. The work done BY a machine

  11. ANSWER • Work input is… • C. The work done ON a machine

  12. 6. What is work output? • A. A number that tells how many times a machine multiplies a force • B. A quantity, usually expressed as a percentage, that measures the ratio of work output to work input • C. The work done ON a machine • D. The work done BY a machine

  13. ANSWER • Work output is… • D. The work done BY a machine

  14. 7. What is mechanical advantage? • A. A number that tells how many times a machine multiplies a force • B. A quantity, usually expressed as a percentage, that measures the ratio of work output to work input • C. The work done ON a machine • D. The work done BY a machine

  15. ANSWER Mechanical advantage is… • A. A number that tells how many times a machine multiplies a force

  16. 8. What is mechanical efficiency? • A. A number that tells how many times a machine multiplies a force • B. A quantity, usually expressed as a percentage, that measures the ratio of work output to work input • C. The work done ON a machine • D. The work done BY a machine

  17. ANSWER Mechanical efficiency is… • B. A quantity, usually expressed as a percentage, that measures the ratio of work output to work input

  18. 9. In which situation is a person doing work on an object? • A. A school crossing guard raises a stop sign that weighs 10 N. • B. A student walks while wearing a backpack that weighs 15 N. • C. A man exerts 350 N force on a rope attached to a house. • D. A worker holds a box 1 m off the floor.

  19. ANSWER • A. A school crossing guard raises a stop sign that weighs 10 N.

  20. 10. Scott applies a force of 100 N to move a box 5 meters. How much work did he do? • A. 100 J • B. 500 J • C. 5 J • D. 500 N

  21. ANSWER • B. 500 J

  22. 11. If a barbell weighs 160 N, what other information do you need to calculate how much work it takes to lift it? • A.The shape of the weights • B.The height the barbell is being lifted • C.The strength of the person doing the lifting • D.The amount of output force

  23. ANSWER • B. The height the barbell is being lifted

  24. 12. Tom used 75 N of force to push a box 3 m across the floor. How much work did he do? • 25 J • 25 N • 225 J • 225 W

  25. ANSWER 75 N x 3 m = c. 225 J

  26. 13. Which of the following prevents machines from being 100% efficient? • friction • input force • output force • power

  27. ANSWER a. friction

  28. GOOD LUCK ON TUESDAY!! STUDY HARD!! A copy of this guide is available on our websites: Frost.sd54.org/mrcscience and Frost.sd54.org/dzuffante

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