# Forces & Energy

When a force (F) moves and object through a distance (d) then work is done and energy is transferred.

Work done (W) is measured in joules (J). Energy transferred is measured in joules (J).

Work done = Energy Transferred

Work done       =          force            x         distance moved

(joules, J)               (newtons, N)                  (metres, m)

Power

Power (P) is the work done in a given time, it is measured in watts (W). One watt is one joule per second.

Power             =           energy transferred

time

Gravitational Potential Energy

This is the energy an object gains when it is lifted up in a gravitational field, it is measured in joules (J).

change in GPE     =          mass          x     gravitational field strength         x      change in height

(joules, J)          (kilogram, kg)         (newtons per kilogram, N/kg)             (metres, m)

Kinetic energy

The kinetic energy of an object depends on its mass and speed, it is measured in joules (J).