Define power, average power, instantaneous power.

Explanation

Power: Power is defined as the rate of work done or energy delivered.
Power (P) = `("Work done (W)")/("Time taken (t)")`
`P=(W)/(t)`
Average power: The average power `(P_(av))` is defined as the ratio of the total work done to the total time taken.
`P_(av)=("Total work done")/("Total time taken")`
Instantaneous power: The instantaneous power `(P_("inst"))` is defined as the power delivered at an instant (as time interval approaches zero).
`P_("inst")=(dW)/(dt)`