Chapter 4, Problem 43R

To determine

To explain: Something that cannot be done by machines.

Explanation of Solution

Introduction:

A device that increases force or changes the motion from the work on it is known as machine.

Example of a machine that increases force is a ‘car jack’, example of a machine that changes direction of force is a ‘wedge shaped blade of the axe’ and example of a machine that increases velocity is a ‘bicycle’. However, machines cannot increase work. Work depends upon force and motion. There are no machines that can increase force and can change speed both at the same time. More work is put into a machine than obtained from a machine. This is a fundamental scientific law and cannot be broken by building better machines.

Conclusion:

A machine cannot increase work.