(a)[2]
State two SI base units excluding the kilogram, metre and second.
(b)
A metal wire with original length $l_0$ is hung vertically, as shown in Fig. 1.1. The wire’s weight makes it stretch, and the elastic potential energy stored in the wire is $E$.
(b(i))[2]
Show that the SI base units of $E$ are $\text{kg m}^2 \text{s}^{-2}$.
(b(ii))[3]
The elastic potential energy $E$ is given 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, $A$ is the cross-sectional area of the wire, and $C$ is a constant. Determine the SI base units of $C$.