8. 25 pt. 5 pt. 10 pt. 15 pt. 20 pt. 25 pt. 5 pt. 10 pt. 15 pt. 20 pt. 25 pt. 5 pt. 10 pt. 15 pt. 20 pt. 25 pt. 5 pt. 10 pt. 15 pt. 20 pt. 25 pt. 5 pt. 10 pt. 15 pt. 20 pt.

9. 1-5 When energy is added to an object, what kind of work is done? A) positive B) negative C) zero D) not enough info

10. 1-5A When energy is added to an object, what kind of work is done? A) positive

11. 1-10 Is the work done on the object pictured below positive or negative? distance Force

12. 1-10A Zero, since the force and distance are at right angles. Is the work done on the object pictured below positive or negative? distance Force

13. 1-15 How much work is done by a car’s engine when it pushes with a force of 1450 N through a distance of 200 meters?

14. 1-15A How much work is done by a car’s engine when it pushes with a force of 1450 N through a distance of 200 meters? Work = Force x distance Work = (1450 N)(200 m) = 290,000 J

15. 1-20 How many watts are expended when a 100-N person walks 3.5 meters up a flight of stairs in 14 seconds?

16. 1-20A How many watts are expended when a 100-N person walks 3.5 meters up a flight of stairs in 14 seconds? Work = Force x distance Work = (100 N)(3.5 m) = 350 J Power = Work / Time Power = (350 J)/(14 sec) = 25 Watts

17. 1-25 Suppose that a block of weight 300-N is lifted through a height of 5 meters by pushing it up a ramp 16.5 meters long. How hard must the block be pushed up the ramp? 5 m 16.5 m F

18. 1-25A Suppose that a block of weight 300-N is lifted through a height of 5 meters by pushing it up a ramp 16.5 meters long. How hard must the block be pushed up the ramp? 5 m 16.5 m F Energy needed = weight x height = (300 N)(5 m) = 1500 J Work on Ramp = 1500 J Work = Force x distance Force = Work / distance = (1500 J)/(16.5 m) = 90.9 Newtons

19. 2-5 Negative work is done on a rolling bowling ball. What happens to the kinetic energy of the ball? A) KE increases B) KE does not change C) KE decreases D) not enough info

20. 2-5A Negative work is done on a rolling bowling ball. What happens to the kinetic energy of the ball? C) KE decreases

21. 2-10 True or False: It is possible for an object to have a negative kinetic energy.

22. 2-10A False True or False: It is possible for an object to have a negative kinetic energy.

23. 2-15 What is the KE of a car with mass 1200-kg that is moving at 50 m/sec?

24. 2-15A KE = 1 / 2 mv 2 KE = 1 / 2 (1200 kg)(50 m/s) 2 KE = 1,500,000 Joules What is the KE of a car with mass 1200-kg that is moving at 50 m/sec?

25. 2-20 Two identical cars are traveling down the road -- one moving at twice the speed of the other. If both apply the brakes, what will happen? A) they both travel the same distance B) the faster car will move twice as far C) the faster car will move four times as far D) not enough info

26. 2-20A Two identical cars are traveling down the road -- one moving at twice the speed of the other. If both apply the brakes, what will happen? C) the faster car will move four times as far

27. 2-25 A rocket of mass 250-kg is pushed by a thrust force of 10,000-N through 12 kilometers. How fast is it moving when the engine shuts off?

28. 2-25A Work = Change in KE ==> Fd = 1 / 2 mv 2 (10,000 N)(12,000 m) = 1 / 2 (250 kg)v 2 v = √[2(10,000 N)(12,000 m)/250 kg] v = 980 m/sec A rocket of mass 250-kg is pushed by a thrust force of 10,000-N through 12 kilometers. How fast is it moving when the engine shuts off?

29. 3-5 How do you calculate gravitational potential energy (GPE)?

30. 3-5A GPE = weight x height = mgh How do you calculate gravitational potential energy (GPE)?

31. 3-10 What is the GPE of a 50-kg object placed at a height of 10 m?

32. 3-10A GPE = mgh = (50 kg)(10 m/s 2 )(10 m) GPE = 5,000 Joules What is the GPE of a 50-kg object placed at a height of 10 m?

33. 3-15 A perfect pendulum swings from rest. How high does it go before it stops? A) lower than originally B) the same height as originally C) higher than originally D) not enough info

34. 3-15A A perfect pendulum swings from rest. How high does it go before it stops? B)the same height as originally

35. 3-20 An elevator of 550-kg goes from the first to the fourth floor. If each floor is 4 meters, how much GPE does the elevator gain?

36. 3-20A Weight = 550 kg * 10 m/s 2 = 5,500 N GPE = weight x height = (5,500 N)(3 x 4 m) (it’s 3 flights from 1 st to 4 th floor) GPE = 66,000 Joules An elevator of 550-kg goes from the first to the fourth floor. If each floor is 4 meters, how much GPE does the elevator gain?

37. 3-25

38. 3-25A GPE = (2300 kg)(10 m/s 2 )(38 m) = 874,000 J Power = GPE / Time = (874,000 J)/(60 sec) Power = 14,567 Watts How much power does the engine of a 2300-kg elevator put out if it climbs through 38-m in one minute?

39. 4-5 If the universe began during the Big Bang 14 billion years ago with an energy of 516 gadzillion Joules, how much energy is there in the universe right now?

40. 4-5A If the universe began during the Big Bang 14 billion years ago with an energy of 516 gadzillion Joules, how much energy is there in the universe right now? 516 gadzillion Joules

41. 4-10 When a car slows down to a stop where does all of its previous KE go? A) it turns into heat B) braking energy C) into total mechanical energy D) not enough info

42. 4-10A When a car slows down to a stop where does all of its previous KE go? A)it turns into heat

43. 4-15 When a diver who weighs 650-N jumps from a 10-m high diving platform, how much KE do they hit the water with?

44. 4-15A GPE initial = KE final KE final = (650 N)(10 m) = 6500 J When a diver who weighs 650-N jumps from a 10-m high diving platform, how much KE do they hit the water with?

45. 4-20 When jumping up and down on a trampoline, the 450-N jumper leaves the trampoline with a KE of 3800 J. How high do they travel?

46. 4-20A KE initial = GPE final = mgh 3800 J = (450 N) h h = (3800 J)/(450 N) = 8.44 m When jumping up and down on a trampoline, the 450-N jumper leaves the trampoline with a KE of 3800 J. How high do they travel?

47. 4-25 A 2-kg ball slides from rest down a 5-m tall incline as shown. When it is halfway down, how fast is it going?

48. 4-25A GPE initial = KE + GPE (2kg)(10m/s 2 )(5m) = 1 / 2 (2kg)v 2 + (2kg)(10m/s 2 )(2.5m) 100 J = 1 / 2 (2kg)v 2 + 50 J 50 J = v 2 v = √(50) = 7.1 m/sec A 2-kg ball slides from rest down a 5-m tall incline as shown. When it is halfway down, how fast is it going?

49. 5-5 Where on Earth would you have the greatest gravitational potential energy?

50. 5-5A Mount Everest Where on Earth would you have the greatest gravitational potential energy?

51. 5-10 Name the character and movie that produced this famous quote: “A wizard is never late… he arrives precisely when he means to.”

52. 5-10A Gandalf the Grey, in LOTR: Fellowship of the Ring

53. 5-15 What is the name of the very energetic fitness guru who exercised to the oldies in the 1990’s?

54. 5-15A Richard Simmons

55. 5-20 In what year was the Great Pyramid of Giza constructed? (±200 years)

56. 5-20A Roughly 2600 B.C.E.

57. 5-25 Who is the vicious ruler of the planet Mongo?

58. 5-25A Ming the Merciless

59. Daily Double How much power does the engine of a 2300-kg elevator put out if it climbs through 38-m in one minute?