How long will it take for the water heater to turn a tankful of cold water into hot water?

Question

An electrical water heater can deliver 4500 Watts (which means, 4500 Joules per second).

Answer 1

It depends on the temperatures involved and the amount of water present.

WD=mc(change T)

where WD = work done, m = mass water, c= specific heat capacity of water (c=4.186), T= temperature

To solve the problem, you would find the work required to heat the water from the cold to hot by substituting the values of mass and temp. Then you would divide this by the power of the heater to find the time taken.