Pressure in liquids and gasesIB MYP Physics: Flashcards

Exam questions on Pressure in liquids and gases

1. A hydroelectric dam in Norway holds back a deep reservoir of fresh water. The wall of the dam is built much thicker at the bottom than at the top. Fresh water has a density of 1000 kg/m³. Use g = 10 N/kg.
   A second dam holds back sea water, of density 1030 kg/m³, to the same depth. State and explain how the pressure at the base of the second dam compares with the first.2 marks
2. A car garage in Nairobi uses a hydraulic lift. A mechanic pushes a small piston of area 0.004 m² with a force of 150 N. The liquid transmits the pressure to a large piston of area 0.20 m² underneath the car.
   Explain why the large piston can exert a much greater force than the force applied to the small piston.2 marks
3. A student investigates how pressure changes with depth in a liquid. She fills a tall plastic bottle with water and makes three small holes of the same size, one above the other, at heights of 5 cm, 15 cm and 25 cm above the base. She covers the holes with tape, keeps the bottle full, removes the tape and measures how far each jet of water lands from the bottle on a flat table.
   State a testable hypothesis for this investigation and give a scientific reason for it.3 marks