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## Work

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**Work**“Quiz” tomorrow**You lift a 3 N book 2 m. How much work did you do?**• 3 N x 2 m = • 6 J**If 40 J of work is done on a 2 N object, how far did it go?**• 40 J/2 N= • 20 m**You lift two 4 N books 2 m. How much work did you do?**• (4N + 4N) x 2m = • 16 J**A crew member uses 800 N to row an oar’s handle 0.5 m. How**much work did the crew member do? • 800 N x 0.5 m = • 400 J**You lift your 50 N cousin 1.5 m. How much work do you do?**50 N x 1.5 m = 75 J**You went shopping and filled two bags. You need to carry**both bags up the stairs. Would you do more work if you carried one bag at a time or both bags at the same time? • The work would be the same (one bag at a time would be more distance, since you would lift the bag up the stairs twice, though it would be ½ the N, and two bags would be ½ the distance, since you’d only be going upstairs once).**A giraffe lifts his 3 N head 2 m. How much work did he do to**reach the food on the top branch? • 3 N x 2 m = • 6 J**A soccer player kicks a 1 N ball 8 m to the goal. How much**work would the goalie have to do in order to stop the ball? • 1 N x -8 m = • -8 J • Negative because the goalie is working opposite the kicker.**A student lifts three 3 N books 0.5 m. How much work did the**student do? • (3 x 3 N) x 0.5 m = • 4.5 J**Who did more work: a girl who lifts five 1 N boxes 1 m or**another girl who carries a 7 N suitcase 3 m? • First girl: • (5 x 1 N) x 1 m= • 5 J • Second girl: • 7 N x 0 m (she is not carrying the suitcase in the direction of the work!) = • 0 J • The girl with the boxes