Act8_sol

# Act8_sol - Per 8 Activity Solutions Work Efficiency and...

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29 Per 8 Activity Solutions: Work, Efficiency, and Complex Machines 8.1 How Much Work is Done by Machines? How Efficient Are They? a) Block and Tackle Your instructor will use the block and tackle to lift blocks. 1) How much weight did the block and tackle lift? _______________ 2) How high off the floor were the cement blocks raised? _______________ 3) Find the work done on the blocks to raise them. This is the work out . Work out = F out x D out ___________ 4) How much force was needed to raise the blocks? _______________ 5) Through what distance was the rope pulled to lift them? ________________ 6) Find the work done when you pull the block and tackle rope. This is the work in . Work in = F in x D in _____________ 7) Calculate the efficiency of the block and tackle. in out Work Work Efficiency = b) Winch Try a “tug of war” game with the winch in the front of the classroom. 1) Suppose you move the handle of the winch in a circle a distance of 112 meters (distance in). When you do, the winch rope moves 2 meters (distance out). If you exert a force of 280 newtons on the winch handle (force in), calculate how much work in must you do to move the winch handle a distance of 112 m. Work in = F in x D in = 280 N x 112 m = 31,360 joules __ 3.14 x 10 4 J __ 2) If the force out on the rope is 8,400 newtons, how much work out does the winch do as it pulls the rope a distance of 2 m? Work out = F out x D out = 8,400 N x 2 m = 16,800 joules __ 1.68 x 10 4 J ___ 3) Calculate the efficiency of the winch. Efficiency

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Act8_sol - Per 8 Activity Solutions Work Efficiency and...

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