Question

what does it mean by 85% efficiency of a simple machine ?

Answer 1

85% efficiency of simple machine mean if 85 jule external workdone by the engine in one complete cycle to 100jule amount of heat energy absorbed by the engine.

Answer 2

85% efficiency of simple machine means that with 100% input, the machine will give a work output of 85%.

EXPLANATION:

The efficiency of a machine is the ratio of its Mechanical Advantage to its Velocity. A machine is said to be 100% efficient when this ratio is 1:1. A machine that is 85% efficient will have a ratio of Mechanical Advantage and Velocity as 0.85 which means that it will perform or work a little less when 100% work input is given.