Unit L - Work, Energy & Power

4c (4.11-4.17)

Equation: Work done, Force and Distance

W = Fd

Work done = Force x Distance moved

[J] = [N] x [m]

Work done =

energy transferred

Equation: Gravitational potential energy

GPE = mgh

Gravitational potential energy = Mass x Gravitational field strength x Height

[J] = [kg] x [N/kg] x [m]

Equation: Kinetic energy

KE = ½mv²

Kinetic energy = ½ x Mass x (Speed)²

[J] = ½ x [kg] x ([m/s])²

Falling objects transfer energy

When something falls, energy from GPE store is transferred to its KE store

For a falling object when there’s no air resistance:
Energy lost from GPE store = Energy gained in KE store

Related to Principle of Conservation of Energy

Power

Rate of transfer of energy

Equation: Power, Work done and Time

P = W/t

Power = Work done / Time taken

[W] = [J] / [s]