Pressure (Cambridge (CIE) IGCSE Physics)

Fig.5.1 shows a glass bottle containing air. The bottle is sealed with a cap.

The air in the bottle becomes warmer.

(i) State what happens to the pressure of the air in the bottle.

[1]

(ii) Explain why the pressure of the air in the bottle changes. Use your ideas about gas molecules.

[4]

The bottle has a weight of 5.4 N and an area of 9.2 cm² in contact with the table.

 Calculate the pressure produced by the bottle on the table. Give the unit.

pressure = ......................................................... 

Fig. 5.2 shows another bottle. The bottle is on a table. Part of the base of this bottle is not in contact with the table.

(i) The base of the bottle is circular. The radius of the outer circle is 4.0 cm as shown in Fig. 5.3. Calculate the area of this circle.

area = .................................................. cm² [1]

(ii) The bottle shown in Fig. 5.2 has the same mass as the bottle shown in Fig. 5.1.

Explain why the bottle shown in Fig. 5.2 exerts more pressure on the table than the bottle shown in Fig. 5.1.

[1]

Fig. 4.1 shows a pin. Fig. 4.2 shows a person pushing the pin into a wall.

The area of the top surface of the pin is 1.8 cm².

The person applies a force of 50 N.

Calculate the pressure exerted on the top surface of the pin.      

pressure = ............................................. N / cm² 

The area of the top surface of the pin is 500 times larger than the area of the point.

Calculate the value of the pressure exerted by the point on the wall.      

 pressure = ............................................. N / cm² 

Fig 2.1 shows liquid in a cylinder.

Table 2.1 gives some data about the cylinder and the liquid.

The cylinder containing liquid is placed on a digital balance that displays the mass in kg.

  Calculate the reading shown on the balance.

reading ......................................................kg 

Extended tier only

Fig. 2.2 shows a device called a manometer that measures the pressure of a gas.

(i) The pressure of the gas is 400 Pa greater than atmospheric pressure.

Calculate the density of the liquid.

density = ...........................................................[2]

(ii) With the gas supply connected, the top of the tube on the left of the device is sealed securely with a rubber stopper. The gas pressure is then increased.

State and explain what happens to the liquid in the manometer.

[2]

Extended tier only

On a particular day, the atmospheric pressure is 1.0 × 10⁵ Pa. A bubble of gas forms at a point 5.0 m below the surface of a lake. The density of water is 1000 kg/m³.

Determine

(i) the total pressure at a depth of 5.0 m in the water,

pressure = ...........................................................[3]

(ii) the pressure of the gas in the bubble.

pressure = ...........................................................[1]

Extended tier only

As the bubble rises to the surface, the mass of gas in the bubble stays constant. The temperature of the water in the lake is the same throughout.

Explain why the bubble rises to the surface and why its volume increases as it rises.

Fig. 3.1 shows an archer pulling the string of a bow.

The archer uses a force of 120 N. The force acts on an area of 0.5 cm² on the archer’s fingers.

Calculate the pressure on the archer’s fingers.

pressure on fingers = ............................................ N/cm² 

The archer’s other hand is pushing the bow with the same force of 120 N. This force acts on a larger area than the force in (a).

State whether the pressure on this hand is greater than, the same as or less than the pressure on the fingers holding the string.

State the energy store of the bow that energy is transferred into when the archer bends it as shown in Fig. 3.1.

Fig. 4.1 shows liquid in a cylinder.

The depth of the liquid is 10 cm and the radius of the cylinder is 3.0 cm. The weight of the liquid in the cylinder is 2.5 N.

  Calculate the density of the liquid. You can assume that acceleration of free fall is 10 m/s².

density = ...........................................................

Extended tier only

Fig. 4.2 shows a device called a manometer that measures the pressure of a gas supply.

(i) The difference h between the two liquid levels is 2.0 cm. The density of the liquid is 800 kg/m³.

Calculate the difference between the pressure of the gas and atmospheric pressure.

pressure difference = ...........................................................[2]

(ii) A similar device with a tube of smaller cross-sectional area is connected to a gas supply at the same pressure.

State and explain any effect on the value of h.

[2]

A rectangular container has a base of dimensions 0.12 m × 0.16 m. The container is filled with a liquid. The mass of the liquid in the container is 4.8 kg.

Calculate

(i) the weight of liquid in the container

weight = ...........................................................[1]

(ii) the pressure due to the liquid on the base of the container

pressure = ...........................................................[2]

Explain why the total pressure on the base of the container is greater than the value calculated in (a)(ii).

Extended tier only

The depth of liquid in the container is 0.32 m.

Calculate the density of the liquid.

density = ...........................................................

A scientist fills a container with seawater. The container has dimensions 30 cm × 30 cm × 40 cm. The density of seawater is 1020 kg/m³.

Calculate the mass of the seawater in the container.

mass = .........................................................

Extended tier only

Fig. 2.1 shows a submarine. The submarine is fully submerged in the sea.

(i) The atmospheric pressure is 100 kPa and the total pressure on the top surface of the submarine is 500 kPa.

Calculate the depth of the top surface of the submarine below the surface of the sea.

depth = ......................................................... [3]

(ii) A hatch (an opening door) on the top surface of the submarine has an area of 0.62 m².

Calculate the downward force on the hatch due to the total pressure on the top surface of the submarine.

force = ......................................................... [2]

Fig. 2.1 shows a hollow metal cylinder containing air, floating in the sea.

The density of the metal used to make the cylinder is greater than the density of seawater.

Explain why the cylinder floats.

Extended tier only

The cylinder has a length of 1.8 m. It floats with 1.2 m submerged in the sea. The bottom of the cylinder has an area of cross-section of 0.80 m².

  The density of seawater is 1020 kg/m³. Calculate the force exerted on the bottom of the cylinder due to the depth of the seawater.

force = ...........................................................

Deduce the weight of the cylinder. Explain your answer.

A cylindrical container has a base with diameter of 0.15 m and is filled with water to a depth of 0.35 m as shown in Fig. 1.1.

The mass of the water is 6.2 kg.

Calculate the weight of the water in the container.

Calculate the pressure due to the liquid on the base of the container.

The water-filled cylinder is placed on a laboratory bench.

Suggest reasons why the total pressure on the bench is higher than the value calculated in part (b).

Extended tier only

A bead of hollow glass is dropped into the water and comes to rest floating 12 cm above the base of the cylinder as shown in Fig. 1.2.

Fig. 1.2

 Calculate the total pressure on the bead.

Atmospheric pressure at sea level = 1.01 × 10⁵ Pa

Density of water = 1000 kg/m³