State the value of absolute zero in ∘C^\circ\text{C}∘C.
Explain, in terms of its molecules, how a gas exerts a pressure on the walls of its container.
A hydrostatic pressure switch is used in a rainwater harvesting system to detect when the water level reaches a target depth. The water at the bottom of the tank exerts pressure on a flexible diaphragm, which compresses air inside the sensor. When the total pressure of this air reaches 108 kPa108\text{ kPa}108 kPa, the system triggers a valve to stop filling.
The total pressure measured by the sensor is given by the relationship:
total pressure=atmospheric pressure+pressure difference caused by the water \text{total pressure} = \text{atmospheric pressure} + \text{pressure difference caused by the water} total pressure=atmospheric pressure+pressure difference caused by the waterState the equation linking pressure difference, height (depth), density, and ggg.
Calculate the depth of the water in the tank when the total pressure reaches 108 kPa108\text{ kPa}108 kPa and the valve is triggered.
[atmospheric pressure = 100 kPa100\text{ kPa}100 kPa, density of water = 1000 kg/m31000\text{ kg/m}^31000 kg/m3, gravitational field strength g=10 N/kgg = 10\text{ N/kg}g=10 N/kg]
44 exam-style questions on Edexcel IGCSE Physics Density and pressure. Each one has a worked solution and a mark scheme showing where the marks go.