Physics 9702 · AS & A Level · SI units

SI units — practice question

(a)[2]

State two SI base units apart from kilogram, metre and second.

(b)

A metal wire of original length $l_0$ is hung vertically as shown in Fig. 1.1. Its weight makes it stretch. The elastic potential energy stored in the wire is $E$.

(b(i))[2]

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

(b(ii))[3]

The elastic potential energy $E$ is described by $E = C\rho^{2} g^{2} A l_0^{3}$, where $\rho$ represents the density of the metal, $g$ is the acceleration of free fall, $A$ denotes the cross-sectional area of the wire and $C$ is a constant. Determine the SI base units for $C$.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: kelvin or K

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