Dear teju, 

Here is the definition of kinetic energy as well as it's formula.

Definition -kinetic energy is energy possessed by an object in motion. The earth revolving around the sun, you walking down the street, and molecules moving in space all have kinetic energy.

Formula - The formula for calculating kinetic energy (KE) is KE = 0.5 x mv2. Here m stands for mass, the measure of how much matter is in an object, and v stands for the velocity of the object, or the rate at which the object changes its position.