Pressure

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

Question 1:State three factors that affect the pressure in a liquid. Answer:Factors that affect the pressure in a liquid are– depth (h),– density of liquid (ρ),– gravitational acceleration (g) Question 2:What is the water pressure at a depth of 24 m in a lake? [Density of water, ρ = 1 000 kg m–3 and gravitational … Read more

Aeroplane (Click on the image to enlarge) When a wing in the form of an aerofoil moves in air, the flow of air over the top travels faster and creates a region of low pressure. The flow of air below the wing is slower resulting in a region of higher pressure. The difference between the … Read more

Experiment 1 A paper will be lifted upwards when air is blown rapidly above it. Explanation: Air move rapidly above the paper, causes the pressure above the paper to decrease. Pressure below the paper becomes relatively higher. Owing to the difference of the pressure, a net force is produced to push the paper upward. Experiment … Read more

Bernoulli’s Principle Bernoulli’s Principle states that as the speed of a moving fluid (liquid or gas) increases, the pressure within the fluid decreases. Venturi Effect The Venturi effect is the fluid pressure that results when an incompressible fluid flows through a constricted section of a pipe. Experiment 1 Figure above shows that when water flow … Read more

A balloon filled with helium gas has negligible mass. The volume of the balloon is 120cm³. [Density of air = 1.23 kg/m³.Density of helium gas = 0.18 kg/m³] Calculate the mass of the helium gas in the balloon? m=ρV m=(0.18)(120× 10 −6 )=2.16× 10 −5 kg Find the weight of the helium gas?W=mg W=(2.16× 10 … Read more

Figure above shows a glass tube with cross-sectional area of 10 cm² and mass 10 g. It is filled with lead shots and immerse in water. The tube floats upright in the water. [Density of water is 10 g/cm³] State the name of this device. Hydrometer State one use of this device in a laboratory. To … Read more

Diagram (a) above shows a metal block supported by a spring balance. Diagram (b) shows the block partially immerses in water while diagram (c) shows the block fully immerses in water. What is the mass of the metal block? W = mg(20) = m(10)m = 2kg In diagram b), the reading of the balance became … Read more

Plimsoll Line The Plimsoll line is an imaginary line marking the level at which a ship or boat floats in the water. It indicates how much load is allowed at different types of water Airship Air ship is filled with helium gas. Helium gas has density lower than the surrounding air, hence an upthrust which … Read more