Question

Why is a machine not 100% efficient?

• A. Different parts of the machine are not smooth and rigid
• B. String in it (if any) is not perfectly elastic
• C. Moving parts are not weightless
• D. All of the above

Answer 1

Answer: (A), (B), (C)

The correct options are
A

Different parts of the machine are not smooth and rigid

B

String in it (if any) is not perfectly elastic

C

Moving parts are not weightless

A machine is not 100% efficient because a part of work done on the machine is wasted in overcoming the friction between the various parts of the machine. Its moving parts are not weightless. The string in it (if any) is not perfectly elastic. The different parts of a machine are not perfectly rigid and also not perfectly smooth.