What is Kentic energy

To answer what kinetic energy is, we should look at what energy is. Energy is the capacity of a body to do work. Now, work is done when you move something against a force. So, the greater the capacity of a body to move something against a force, the greater the energy.

Now, let us suppose we have a block of wood on a rough surface. If you gently try to push it, it will not move because of the frictional force on the block by the surface. Now, roll a metal ball onto the block ever so slowly. So slow that the block still doesn't move. So, the energy of your hand and the rolling ball is zero (as far as evidence shows) because neither of them could do work against the frictional force. Now, let us increase the speed of the rolling ball. So high that it can knock the wooden block and move it. Work has been done. So, where did the extra energy come from?

Previously it did zero work and thus had zero energy (mechanical energy to be specific). Now, it could do work and thus has some energy. The only difference between the two tests is the speed. Hence, the energy came from the ball having some motion. This energy is called kinetic energy.