As an object falls from rest, its gravitational potential energy is converted to kinetic energy. Consider a mass m which is falling vertically under the influence of gravity.

Potential Energy = Mass x Gravity x Height

PE = mgh

Kinetic Energy = ½ mv2

KE = ½ mv2

By conservation of energy

Energy before = Energy after

Initial KE + Initial PE = Final KE + Final PE

Object is falling from rest, therefore initial kinetic energy is zero. Once the object hit on the ground, height is zero, therefore no potential energy at ground level.

We can rewrite above equation

Initial PE = Final KE

The mass m on both sides tells us that the final velocity doesn’t depend upon the mass.

Velocity just before the impact is

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