Question

A boy moved a body through $3m$ in four different ways. In which of the following cases was the work done the maximum?

• A. Pushing a body over an inclined plane
• B. Lifting a body vertically upwards
• C. Pushing a body over smooth rollers
• D. Pushing on a plane horizontal surface

Answer 1

The correct option is B Lifting a body vertically upwards

Work done will be maximum when the force is applied against the gravitational as it opposes the force.

Mathematically work done = F.x Cos$\theta$ where $\theta$ is the displacement angle

When the body is lifted vertically upwards the displacement angle is 180 degrees and Cos180 is -1.

Hence work done will be maximum when the displacement angle will be 180 degrees i.e vertically upwards.