Question

Which of the following is NOT a unit of energy?
joule
newtonmetre
kilowatthour
watt

Answer 1

Answer on Question #51057, Physics, Mechanics | Kinematics | Dynamics

The default unit of energy in SI system is Joule, which is by definition equal to the energy transferred to object by moving it 1 metre by the force of 1 Newton. Thus, $1J = 1N \cdot 1m$ and the variants "joule" and "newtonmetre" are indeed units of energy. Since by definition of power $P = \frac{dA}{dt}$, or average power over time $t$, $P = \frac{A}{t}$ and power is measured in watts, kilowatthour has dimension $[P][t]$ and therefore it is also the unit of energy. As already mentioned, watt is a unit of power, not energy, thus the correct answer is **watt**.

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