Question

Which of the following statements supports the non-existence of an ideal machine?

• A. Moving parts are not frictionless.
• B. String is not perfectly elastic.
• C. Different parts are not perfectly rigid.
• D. All the input work is converted to output work.

Answer 1

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

The correct options are
A Moving parts are not frictionless.
B String is not perfectly elastic.
C Different parts are not perfectly rigid.

As we all know, an ideal machine does not exist. Because moving parts of a machine is neither weightless nor frictionless. The strings are not perfectly elastic and different parts of the machines are not perfectly rigid. However an actual machine cannot convert the input work completely into output work, because some of the energy is lost due to friction.