Question

how many joules of energy are consumed by a 1000w heater used for 2hrs

Answer 1

Energy consumed in 2hrs= 1kWh

Energy consumed in 1hr= 0.5kwh

So,

1kWh=3.6×10^6j

0.5kWh=1.8×10^6j

Therefore

Energy consumed in 2hrs = 2×1.8×10^6j =3.6×10^6j

This is the full explanation. It can be written in a much condensed form. Hope this helps.