Physics 9702 · AS & A Level · SI units

SI units — practice question

(a(i))[1]

Define the term power.

(a(ii))[1]

Show that the SI base units for power are $\text{kg m}^2 \text{s}^{-3}$.

(b(i))[2]

Every body emits energy. The power $P$ radiated by a body is given by $P = kAT^4$, where $T$ is the thermodynamic temperature of the body, $A$ is the surface area of the body and $k$ is a constant. Determine the SI base units of $k$.

(b(ii))[1]

On Fig. 1.1, sketch how $P$ varies with $T^2$. Keep $A$ constant.

Worked solution & mark scheme

This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: Power is the work done per unit time, or the energy transferred per unit time.

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