In practice, the work output of a machine is always less than the work input due to the effect of ______.

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RRB ALP Electrician 22 Jan 2019 Official Paper (Shift 3)

Answer 1

Concept:

Friction:

The force that resists the sliding or rolling of one solid object over another.
Frictional forces, such as the traction needed to walk without slipping, may be beneficial, but they also present a great measure of opposition to the motion.

Efficiency:

The efficiency of a machine is the ratio of the work done on the load by the machine to the work done on the machine by the effort.
Thus, it is the ratio of useful work done by the machine output to the work done by the machine input.
It is represented by the Greek symbol η.
Formula, efficiency, \(\eta=\frac{output\, \, workdone}{input\, \, work done}\)

Explanation:

In practice, the work output of a machine is always less than the work input due to the effect of friction.
The work output of a machine is never equal to the work input because some of the work done by the engine is used to overcome the friction created by the use of the device.
Hence, the efficiency of the machine can never be 100%.