A stratospheric research balloon is filled with helium gas on the ground and released to carry scientific instruments into the upper atmosphere.
Describe the effect of a decrease in temperature on the average speed of the helium molecules inside the balloon.
The helium gas inside the balloon exerts a pressure on the inner surface of the fabric. Use ideas about molecules to explain how the gas causes this pressure.
Explain, in terms of density, why the balloon rises through the lower atmosphere.
At a high altitude, the average density of the helium gas inside the balloon is 0.18 kg/m30.18 \text{ kg/m}^30.18 kg/m3. The volume of this gas is 5400 m35400 \text{ m}^35400 m3.
(i) State the equation linking density, mass, and volume.
Calculate the mass of the helium gas inside the balloon.
As the weather balloon climbs higher into the stratosphere, the atmospheric air pressure outside the balloon decreases.
(i) Suggest a reason for this decrease in external atmospheric pressure.
Suggest how a decrease in outside air pressure affects the volume of a flexible, sealed balloon.
51 exam-style questions on Edexcel IGCSE Physics Ideal gas molecules. Each one has a worked solution and a mark scheme showing where the marks go.