# Impact energy

** The impact energy** is a measure of the work done to fracture a test specimen (for example, grinding balls), usually measured in joules. There is simplified formula of impact energy:

**E = m × g × h**,

** m** is the mass (kg),

** g** is 9.8 m / s

^{2},

** h** is the load drop height .

Impact energy of the grinding bodies directly depends on the correctly chosen speed mode of the mill. Material shredding by the impact of the ball occurs due to direct strike caused by the radial velocity acting along the impact line. The tangential speed of impact contributes only to moving the ball along the circular trajectory if its direction coincides with the direction of drum rotation. With this, the grinding of ore occurs due to crushing and abrasion. All the kinetic energy of the ball at the end of the parabolic path is: E = m * v^{2}. Only a fraction of this amount of energy is spent on chopping. It is equal to **Е****= m*v ^{2.}**