Consider a baseball flying through the air. The ball is said to have “kinetic energy” by virtue of the fact that its in motion relative to the ground. You can see that it is has energy because it can do “work” on an object on the ground if it collides with it (either by pushing on it and/or damaging it during the collision).

The formula for Kinetic energy, and for some of the other forms of energy described in this section will, is given in a later section of this primer.