The time rate of work done by a body is called its power.
Power = Rate of doing work = Work done / Time taken
If under a constant force F a body is displaced through a distance s in time t, the power
p = W / t = F * s / t
But s / t = v ; uniform velocity with which body is displaced.
∴ P = F * v = F v cos θ
where θ is the smaller angle between F and v.
power is a scalar quantity. Its S1 unit is watt and its dimensional formula is [ML2T-3].
Its other units are kilowatt and horse power,
1 kilowatt = 1000 watt
1 horse power = 746 watt