May/June 2026 Paper 43

A balloon contains helium gas. Explain how the particles of helium gas in the balloon exert a pressure on the inside of the balloon.

The balloon contains a volume of 12 m${}^3$ of helium gas at a pressure of 110 kPa. The balloon is released and rises to a height $h$ where the pressure of the gas is 52 kPa. The temperature and the mass of helium gas remain constant. Calculate the volume of the helium gas at height $h$.

At height $h$, the balloon has gained 120 kJ of energy in the gravitational potential store. The mass of the balloon is 2.5 kg. Calculate the height $h$.