A cube of aluminium measures 1 m along each side. In the centre of the cube there is a small spherical cavity with a diameter of 1 cm. When the cube is heated from 10 ◦C to 30 ◦C, what is the percentage increase in the volume of the central cavity? (The lin- ear thermal expansion coefficient of aluminium is 23 × 10−6 K−1 .) 0.14%