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. 10 joules of work input to operate. What is the
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Given: Work output == 8 J
Work input. = ·10 J
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Unknown: Efficiency
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Equation: Efficiency = Work input X 100%
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Solution: Efficiency = 10 J X 100%
Example 4:
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What is the work output of a machine that has a work
input of 2,800joules and an efficiency of 923, percent?
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Given: Work input: 2,800 J
Efficiency = 92.3%
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Unknown: Work output
Work output
Equation: Efficiency =, W or k"mpu
Solution: Solve the equation for work output:
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Work output = 92.5% x 2,800 J = 2,590 J
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Practice Exercises
Exercise 1:
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A ski lift carries people along a 220-meter cable up the
side of a mountain. Riders are lifted a total of
110 meters in elevation. What is the ideal mechanical
advantage of the ski lift?
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The ideal mechanical advantage. of a machine is 3.2 and
its output distance is 2.5 meters. What is the input
distance?
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Physical Science Math Skills and Problem Solving Workbook
57
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