A weather balloon is filled with helium. The volume of the balloon is 6.0 m3.
The total weight of the balloon, the helium and the instruments it carries is 50 N.
At ground level, the density of the air is 1.2 kg/m3. The gravitational field strength, ggg, is 10 N/kg.
Calculate the upthrust on the balloon at ground level.
Calculate the resultant force on the balloon when it is released at ground level.
Give the direction of the resultant force.
The density of the air decreases as the height above the ground increases.
The volume of the balloon does not change.
Explain why there is a height above which the balloon cannot rise.
132 exam-style questions on Edexcel GCSE Physics 15.2 Pressure in fluids, covering 15.2.1 Atmospheric pressure and height, 15.2.2 Pressure in fluids, 15.2.3 Pressure, force and area, 15.2.4 Pressure and depth, 15.2.5 Pressure in liquids: depth and density, 15.2.6 Upthrust, and 15.2.7 Floating and sinking. Each one has a worked solution and a mark scheme showing where the marks go.