Find the efficiency of a machine that does 800J of work if the input work is 2,000J

Efficiency: 0.4 (40%)

Explanation:

The efficiency of a simple machine is given by the ratio

n = w¹/w²

where

w² is the input work of the machine

w¹ is the output work of the machine

For the machine in this problem, we have:

w¹ = 800j is the output work

w² = 2000j is the input work

Therefore, the efficiency of the machine is

n = 800/2000 = 0.4

Which can be also written as percentage:

n = 0.4 × 100 = 40%

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