Pressure

Question 11:Photograph 1 shows a racing car that is stabilised by downforce while being driven at high speed.Explain the production of the downforce due to the air flowing past the: (a) inverted aerofoil-shaped spoiler(b) top and bottom sections of the car Answer:(a) Air flows at a lower velocity past the upper surface of the aerofoil … Read more

Question 9:A hot air balloon is in a stationary position in the air.(a) State Archimedes’ principle.(b) Explain the relationship between the weight of the balloon and the weight of air displaced.(c) When the flame of the burner is extinguished and the parachute valve is opened, the balloon begins to descend. Explain how this action enables … Read more

Question 7:A wooden block with volume 3.24 × 10–3 m3 is released in a tank of water. By doing the relevant calculations, sketch the state of buoyancy of the wooden block in the tank.[Density of wood, ρ = 920 kg m–3, density of water, ρ = 1 000 kg m–3 and gravitational acceleration, g = … Read more

Question 4:Figure 2 shows a U-tube containing mercury.(a) What is the pressure acting on point X and point Y on the surface of mercury?(b) By comparing the pressure at point X and point Z, explain why the height of the mercury column, h is a measure of atmospheric pressure.(c) Determine the atmospheric pressure in Pa.[Density … Read more

Question 1:(a) Derive the formula for pressure at depth h in a liquid with density ρ.(b) Calculate the pressure at depth of 24 m in a lake that contains water with a density of 1 120 kg m–3. [Gravitational acceleration, g = 9.81 m s–2] Answer: (a)Consider a liquid column in a containerHeight of liquid … Read more

Question 1:State Bernoulli’s principle. Answer:Bernoulli’s principle states that when the velocity of the flow of a fluid increases, the pressure in the fluid decreases. Question 2:Explain three ways of using a piece of A4 paper to demonstrate Bernoulli’s principle. Answer: Question 3:Figure 2.53 shows the cross section of the wing of an aeroplane when the … Read more

Question 1:State Archimedes’ principle. Answer:Archimedes’ principle states that an object which is partially or fully immersed in a fluid will experience a buoyant force equal to the weight of fluid displaced. Question 2:A small boat displaces 3.8 × 10–2 m3 of sea water. Calculate the buoyant force acting on the boat.[Density of sea water, ρ … Read more

Question 1:State Pascal’s principle. Answer:Pascal’s principle states that the pressure applied on an enclosed fluid is transmitted uniformly in all directions in the fluid. Question 2:Describe how a hydraulic machine can achieve force multiplication by applying Pascal’s principle. Answer:A small force, F1 exerts pressure on the liquid below the small piston.$$ \text { Pressure }=\frac{F_1}{A_1} … Read more

Question 1:Figure 2.21 shows a water manometer connected to a flask containing gas.(a) Compare the gas pressure in the flask with the atmospheric pressure.(b) State the difference between the gas pressure and the atmospheric pressure in m H2O.(c) Calculate the gas pressure in pascal.[Density of water, ρ = 1 000 kg m–3 gravitational acceleration, g … Read more

Question 1:Explain the existence of atmospheric pressure. Answer:Atmospheric pressure is the pressure due to the weight of the layer of air acting on the surface of the earth. Question 2:The height of the mercury column in a barometer is 756 mm Hg on a cloudy day. Calculate the atmospheric pressure at that time in pascal. … Read more