A horizontal force of $20 \mathrm{N}$ is required to keep a body moving in a horizontal direction with constant velocity. What is the work done by frictional force when the displacement of the body is $2 \mathrm{m}?$

Find the work done in lifting a $50 \mathrm{kg}$ bucket of water through a vertical height of $2 \mathrm{m}$. (Take $g = 10 \mathrm{m}/{\mathrm{s}}^2$)

Does the kinetic energy of a body depend on the direction of motion of the object?

When you are climbing stairs, work done by the weight is positive.

Can every force do work?

A book falls freely from the tabletop. Is work done by some force during the fall?