Work is the amount of energy transferred from one type to another. 

Work is measured in Joules.

Work = Force x Distance moved in direction of force

Energy cannot be made or destroyed.

Energy can only be converted from one type to another

Kinetic energy (E_k) is the energy of a moving object.

E_k = 0.5 x mass x velocity²

Gravitational potential energy (E_p) is energy stored in an object because of another objects gravitational field.

ΔE_p = mgΔh

Show that for an object that is dropped a height,Δh, it will have a velocity,v.

v=√(2gΔh)

For a falling object gravitational potential energy is converted into kinetic energy.

So Ek=Ep assuming that the initial speed was zero and that the frictional forces was negligible.

0.5mv²=mgΔh

when re-arranged

v=√(2gΔh)