**Speed** is equal to distance divided by time. **Velocity** is speed in a particular direction. For the purposes of your question, we can think of speed and velocity as being the same thing.

**Kinetic energy (KE)** is the energy of motion. Any object that is in motion has kinetic energy. Kinetic energy is described by the following equation, where m = mass of the object (kg) and v = velocity:

KE = 1/2 x m x `~v^2`

Therefore, the kinetic energy of an object is proportional to the square of its velocity (speed). In other words,

- If there is a twofold increase in speed, the kinetic energy will increase by a factor of four.
- If there is a threefold increase in speed, the kinetic energy will increase by a factor of nine.
- If there is a fourfold increase in speed, the kinetic energy will increase by a factor of sixteen.

**Further Reading**