Question

A body is moved through a distance of 5m in the following different ways. Maximum work is done when the body is:

• A. pushed over an inclined plane
• B. pushed over smooth rollers
• C. raised vertically upwards
• D. pushed on a plane horizontal surface

Answer 1

Answer: (C)

raised vertically upwards

Work done is given by F.S(dot product of force and displacement).

When body moves along inclined plane force required is $mgSin\theta$.

When body moves vertically upwards then force required is mg.

When body moves horizontally force required is equal to the frictional force which is $\mu .mg$ where $\mu$ is generally between 1 and 0 .

So maximum force is required when moving vertically upwards and displacement in each case is same.

When pushed over smooth roller then force required is almost zero. So work done is zero.

So maximum work done is in case of vertically upwards.