An aluminium rod is 20.0 cm long at 20°C and has a mass of 350 g. If 10,000 J of energy is added to the rod by heat, what is the change in length of the rod? (Coefficient of linear expansion of aluminium is 24 x 10^-6 (°C)^-1 and specific heat is 900 J. kg^-1°C.

$\begin{array}{l}\quad \mathrm{W}=\mathrm{ms} \Delta \theta \\ \Rightarrow 10,000=\frac{350}{1000} \times 900 \times \Delta \theta \\ \Rightarrow \Delta \theta=31.746 \\ \text { Again, } l_{2}=l_{1}(1+\alpha \theta) \\ \Rightarrow l_{2}=20\left(1+24 \times 10^{-6} \times 31.746\right)=20.0152 \\ \therefore \Delta l=20.0152-20=0.0152 \mathrm{~cm}=0.15 \mathrm{~mm}\end{array}$