Kinetic Energy

The kinetic energy *E*k is a kind of energy of a moving body. The size of the kinetic energy of a body depends on its mass and velocity. If the body is at rest, it has a zero kinetic energy. Because the movement of bodies is relative, the value of the kinetic energy depends on from what reference system it is observed. The firearms are a model situation here. The equation to calculate the kinetic energy is *E*k = 1/2*m* . *v*², where *m* is the mass of the body, and *v* is the speed of the body.

**Cannonball**

A flying cannonball has a large mass compared to a projectile, but it moves with a lesser speed. Its kinetic energy is large enough to shatter a melon.

**Projectile**

The projectile has a much smaller mass than the cannon ball, but moves with a greater speed. Because the equation for the calculation of the kinetic energy contains the velocity squared (*E*k = 1/2*m* . *v*²), the projectile with considerably less weight can achieve a greater kinetic energy because of the greater speed, which is growing exponentially.

The animation demonstrates that a body with a greater speed gains a greater kinetic energy.