IGCSE Physics 1.8 Pressure MCQs – 30 Practice Questions with Answers (Cambridge 0625)

These 30 original practice questions cover Cambridge IGCSE Physics (0625) Section 1.8, Pressure: pressure in solids, pressure in liquids (including hydraulic systems), and gas and atmospheric pressure. Try each question first, then open the answer to check the full worked explanation. Unless stated otherwise, take g = 10 N/kg.

Formula recap: pressure p = F / A  |  pressure in a liquid p = ρ g h  |  Boyle’s law: pV = constant (fixed mass of gas at constant temperature). Full list: IGCSE Physics Formula Sheet

Pressure in Solids: p = F/A

Q1. Pressure is defined as

  • (A) force multiplied by area
  • (B) force per unit area
  • (C) area per unit force
  • (D) mass per unit volume
Show Answer

Answer: B – Pressure is the force acting normally (at right angles) per unit area of a surface: p = F / A.

Q2. The SI unit of pressure is the

  • (A) newton
  • (B) joule
  • (C) pascal
  • (D) watt
Show Answer

Answer: C – The unit is the pascal (Pa), where 1 Pa = 1 N/m2.

Q3. A force of 200 N acts at right angles on a surface of area 0.50 m2. What is the pressure on the surface?

  • (A) 100 Pa
  • (B) 40 Pa
  • (C) 1000 Pa
  • (D) 400 Pa
Show Answer

Answer: D – p = F / A = 200 / 0.50 = 400 Pa.

Q4. A weight of 60 N rests on a contact area of 30 cm2. What is the pressure exerted on the ground?

  • (A) 2 Pa
  • (B) 200 Pa
  • (C) 2.0 × 104 Pa
  • (D) 2.0 × 105 Pa
Show Answer

Answer: C – First convert the area: 30 cm2 = 30 × 10-4 m2 = 3.0 × 10-3 m2. Then p = F / A = 60 / (3.0 × 10-3) = 2.0 × 104 Pa. (Dividing 60 by 30 without converting the units gives the trap answer of 2.)

Q5. The pressure at the base of a machine is 5000 Pa and the base has an area of 0.02 m2. What is the weight of the machine?

  • (A) 100 N
  • (B) 250 000 N
  • (C) 10 N
  • (D) 250 N
Show Answer

Answer: A – Rearrange p = F / A to get F = pA = 5000 × 0.02 = 100 N.

Q6. A crate of weight 800 N must not exert a pressure greater than 4000 Pa on a floor. What is the minimum area of the base of the crate?

  • (A) 5.0 m2
  • (B) 0.20 m2
  • (C) 0.050 m2
  • (D) 3.2 m2
Show Answer

Answer: B – A = F / p = 800 / 4000 = 0.20 m2. A larger area would reduce the pressure further, so this is the minimum area needed.

Q7. A sharp knife cuts food more easily than a blunt knife because, for the same force,

  • (A) the small area of the sharp edge produces a much larger pressure
  • (B) the sharp knife is heavier
  • (C) the force applied to the food becomes larger
  • (D) the area of contact with the food is larger
Show Answer

Answer: A – p = F / A. The force is the same, but the sharp edge has a very small area, so the pressure on the food is much greater and it cuts through.

Q8. A person walking on soft snow wears snowshoes. The snowshoes help because they

  • (A) increase the pressure on the snow
  • (B) increase the weight of the person
  • (C) reduce the friction between the feet and the snow
  • (D) spread the person’s weight over a larger area, reducing the pressure
Show Answer

Answer: D – The weight (force) is unchanged, but the larger area means p = F / A is smaller, so the person does not sink into the snow. Wide tyres on tractors and heavy vehicles work in the same way on soft ground.

Q9. A drawing pin has a wide flat head and a short sharp point. The sharp point enters a board easily because

  • (A) the pin is made of a very hard metal
  • (B) the point decreases the pressure at the tip
  • (C) the very small area of the point produces a very large pressure for a small force
  • (D) the wide head increases the mass of the pin
Show Answer

Answer: C – A small push on the head (small force) is concentrated on the tiny area of the point, giving a very large pressure p = F / A, so the point pushes into the board.

Q10. Two boxes each weigh 100 N. Box X has a base area of 0.25 m2 and box Y has a base area of 0.50 m2. Which box exerts the greater pressure on the floor, and what is that pressure?

  • (A) Box X, 400 Pa
  • (B) Box Y, 400 Pa
  • (C) Box X, 200 Pa
  • (D) Both boxes, 300 Pa
Show Answer

Answer: A – Box X: p = 100 / 0.25 = 400 Pa. Box Y: p = 100 / 0.50 = 200 Pa. For the same force, the smaller area gives the larger pressure.

Pressure in Liquids

Q11. The pressure at a point inside a liquid increases when

  • (A) the container holding the liquid is made wider
  • (B) the depth of the point below the surface increases
  • (C) the total volume of liquid in the container increases
  • (D) the surface area of the liquid increases
Show Answer

Answer: B – Liquid pressure depends only on the depth below the surface and the density of the liquid (p = ρ g h). It does not depend on the shape of the container or the total volume of liquid.

Q12. What is the pressure due to water at a depth of 2.0 m below the surface? (Density of water = 1000 kg/m3.)

  • (A) 2.0 × 105 Pa
  • (B) 2000 Pa
  • (C) 500 Pa
  • (D) 2.0 × 104 Pa
Show Answer

Answer: D – p = ρ g h = 1000 × 10 × 2.0 = 2.0 × 104 Pa.

Q13. At the same depth below the surface, the pressure in seawater is greater than the pressure in fresh water because

  • (A) the sea is much wider than a lake
  • (B) seawater is colder than fresh water
  • (C) the pressure depends on the shape of the container
  • (D) seawater has a greater density, and p = ρ g h
Show Answer

Answer: D – At the same depth h, p = ρ g h is larger when the density ρ is larger. Seawater is denser than fresh water because of the dissolved salt.

Q14. The wall of a dam is built much thicker at the bottom than at the top. This is because

  • (A) there is more water at the bottom of the reservoir
  • (B) the pressure of the water is greatest at the greatest depth
  • (C) concrete is cheaper near the ground
  • (D) the water temperature is lowest at the bottom
Show Answer

Answer: B – Pressure increases with depth (p = ρ g h), so the force pushing on the dam wall is greatest near the bottom. The wall must be strongest where the pressure is greatest.

Q15. In a hydraulic system, a force of 100 N is applied to a small piston of area 0.01 m2. The pressure is transmitted through the liquid to a large piston of area 0.05 m2. What force is exerted by the large piston?

  • (A) 20 N
  • (B) 100 N
  • (C) 500 N
  • (D) 5000 N
Show Answer

Answer: C – Pressure from the small piston: p = F / A = 100 / 0.01 = 10 000 Pa. This same pressure acts on the large piston, so F = pA = 10 000 × 0.05 = 500 N. The force is multiplied by the ratio of the areas (5 times here).

Q16. A hydraulic machine works because, in an enclosed liquid,

  • (A) pressure is transmitted equally (undiminished) in all directions throughout the liquid
  • (B) the force on every piston is exactly the same
  • (C) the liquid expands when it is compressed
  • (D) energy is created inside the liquid
Show Answer

Answer: A – Pressure applied to an enclosed liquid is transmitted equally throughout the liquid. The force produced depends on the piston area: a larger area gives a larger force for the same pressure (F = pA).

Q17. A U-tube manometer containing water is used to measure a gas pressure. The difference in height between the two water levels is 0.10 m. What is the pressure difference? (Density of water = 1000 kg/m3.)

  • (A) 1000 Pa
  • (B) 100 Pa
  • (C) 10 000 Pa
  • (D) 10 Pa
Show Answer

Answer: A – The pressure difference is balanced by the extra column of water: Δp = ρ g h = 1000 × 10 × 0.10 = 1000 Pa.

Q18. Two containers of very different shapes are filled with water to the same height. The pressure at the base of each container is

  • (A) greater in the wider container, because it holds more water
  • (B) greater in the narrower container, because the water is deeper in the middle
  • (C) the same in both, because the depth and the density are the same
  • (D) impossible to compare without knowing the total volume
Show Answer

Answer: C – p = ρ g h depends only on density and depth. The shape of the container and the total amount of water make no difference.

Q19. Hydraulic brakes in a car use a liquid rather than a gas to transmit pressure because

  • (A) gases are lighter than liquids
  • (B) liquids are usually cheaper than gases
  • (C) gases transmit pressure faster than liquids
  • (D) liquids are almost incompressible, so the pressure is transmitted without being wasted in squeezing the fluid
Show Answer

Answer: D – A gas is easily compressed, so part of the movement of the brake pedal would just squeeze the gas instead of applying the brakes. A liquid barely changes volume, so the pressure is transmitted almost instantly and fully.

Q20. At a certain point inside a tank of water, the pressure due to the water is 30 000 Pa. How far below the surface is the point? (Density of water = 1000 kg/m3.)

  • (A) 0.30 m
  • (B) 30 m
  • (C) 3.0 m
  • (D) 300 m
Show Answer

Answer: C – h = p / (ρ g) = 30 000 / (1000 × 10) = 3.0 m.


Gas Pressure & Atmospheric Pressure

Q21. In the kinetic theory, the pressure of a gas inside a container is caused by

  • (A) the molecules attracting each other strongly
  • (B) the molecules repeatedly colliding with the walls of the container
  • (C) the weight of the molecules resting on the base only
  • (D) the molecules joining together to form a liquid
Show Answer

Answer: B – Gas molecules move randomly at high speed. Each collision with a wall exerts a tiny force, and the very large number of collisions every second produces a steady pressure on the walls.

Q22. A fixed mass of gas is heated in a sealed container of constant volume. Its pressure increases because the molecules

  • (A) become larger when heated
  • (B) increase in number
  • (C) move faster, so they hit the walls harder and more frequently
  • (D) stick together and form a liquid
Show Answer

Answer: C – Heating increases the average speed (and kinetic energy) of the molecules. They collide with the walls more often and with more force, so the pressure rises. The number and size of the molecules do not change.

Q23. A fixed mass of gas has a volume of 200 cm3 at a pressure of 100 kPa. It is slowly compressed to a volume of 50 cm3 at constant temperature. What is the new pressure?

  • (A) 25 kPa
  • (B) 400 kPa
  • (C) 150 kPa
  • (D) 40 kPa
Show Answer

Answer: B – Boyle’s law: p1V1 = p2V2. So p2 = (100 × 200) / 50 = 400 kPa. The volume fell to a quarter, so the pressure rose to four times.

Q24. The pressure of a fixed mass of gas at constant temperature is doubled. What happens to its volume?

  • (A) It doubles.
  • (B) It stays the same.
  • (C) It becomes four times larger.
  • (D) It halves.
Show Answer

Answer: D – By Boyle’s law pV = constant, so pressure and volume are inversely proportional. Doubling the pressure halves the volume.

Q25. The plunger of a sealed syringe is pushed in slowly, keeping the temperature constant. The pressure of the trapped air increases because

  • (A) the molecules are now closer together and collide with the walls more frequently
  • (B) pushing the plunger makes the molecules move faster
  • (C) extra air is pushed into the syringe
  • (D) each molecule expands to fill the smaller space
Show Answer

Answer: A – The same number of molecules is now in a smaller volume, so collisions with the walls happen more frequently. The speed of the molecules is unchanged because the temperature is constant.

Q26. [Supplement] A sealed rigid container of gas is at a pressure of 100 kPa when the temperature is 300 K. The container is heated to 600 K. What is the new pressure? (The volume cannot change.)

  • (A) 100 kPa
  • (B) 50 kPa
  • (C) 200 kPa
  • (D) 150 kPa
Show Answer

Answer: C – For a fixed mass of gas at constant volume, pressure is proportional to the Kelvin temperature (p / T = constant). p2 = 100 × (600 / 300) = 200 kPa. Note: temperatures must be in kelvin, not degrees Celsius.

Q27. A mercury barometer at sea level shows a mercury column 76 cm high. This means that atmospheric pressure

  • (A) is equal to the pressure exerted by a column of mercury 76 cm high
  • (B) is 76 N/m2
  • (C) pushes the mercury down the tube
  • (D) is zero at the top of the column
Show Answer

Answer: A – The air pressure on the mercury in the reservoir supports the column in the tube. Atmospheric pressure is therefore equal to the pressure due to a 76 cm (0.76 m) column of mercury, which is about 1.0 × 105 Pa.

Q28. A sealed packet of crisps expands (puffs up) when taken to the top of a high mountain. This happens because

  • (A) the air inside the packet gets hotter at the top of the mountain
  • (B) the atmospheric pressure outside is lower, so the pressure of the air inside pushes the packet outwards
  • (C) gravity is weaker at the top of the mountain
  • (D) the packet absorbs air from outside
Show Answer

Answer: B – The air sealed inside pushes out with roughly its original pressure, but the outside air pressure decreases with altitude. The pressure difference pushes the packet outwards until it expands.

Q29. A gas is trapped in a sealed container at a pressure of 300 kPa and a volume of 60 cm3. The gas is allowed to expand slowly to a volume of 180 cm3 at constant temperature. What is its new pressure?

  • (A) 900 kPa
  • (B) 100 kPa
  • (C) 33 kPa
  • (D) 180 kPa
Show Answer

Answer: B – Boyle’s law: p2 = p1V1 / V2 = (300 × 60) / 180 = 100 kPa. The volume trebled, so the pressure fell to one third.

Q30. When a person drinks through a straw, the liquid rises up the straw because

  • (A) suction pulls the liquid upwards
  • (B) the pressure inside the straw increases
  • (C) the liquid is attracted to the straw
  • (D) atmospheric pressure on the surface of the drink pushes the liquid up into the straw, where the pressure has been reduced
Show Answer

Answer: D – Sucking removes air and lowers the pressure inside the straw. The higher atmospheric pressure acting on the surface of the drink then pushes the liquid up the straw.

Keep revising: Go back to the IGCSE Physics Formula Sheet for every equation in Section 1.8, or visit the Physics MCQs hub for more IGCSE Physics practice sections, formula sheets and resources for GCSE, IGCSE, A-Level and AP.

All questions on this page are original practice questions written for QuaidianPoint. They are not Cambridge past-paper questions and this page is not affiliated with Cambridge Assessment International Education.