A weather balloon is filled with helium at ground level. The balloon is released and rises through the atmosphere.
At ground level, the volume of the helium is 3.0 m3 and its pressure is 100 kPa.
As the balloon rises, the balloon gets bigger.
Explain why.
At a height of 5 km, the pressure of the helium is 60 kPa.
Assume that the temperature of the helium does not change.
Use the equation: pressure×volume=constant\text{pressure} \times \text{volume} = \text{constant}pressure×volume=constant
Calculate the volume of the helium at this height.
In fact, the temperature of the helium decreases as the balloon rises.
Explain how this affects the volume of the helium compared with your answer to (b).
50 exam-style questions on OCR GCSE Physics 1.3 Pressure, covering 1.3.1 Molecular motion, temperature and gas pressure, 1.3.2 Gas pressure at constant volume, 1.3.3 Compressing and expanding gases, 1.3.4 Gas volume and pressure at constant temperature, 1.3.5 Doing work on a gas, 1.3.6 The Earth's atmosphere and atmospheric pressure, 1.3.7 Atmospheric pressure and height, 1.3.8 Floating and sinking, 1.3.9 Pressure in liquids and upthrust, and 1.3.10 Pressure differences with depth. Each one has a worked solution and a mark scheme showing where the marks go.