Grade 10 physics – Pressure Quiz
1. What is the definition of pressure?
Pressure is defined as the normal force acting on a surface divided by the area of that surface (p = F/A).
2. What is the SI unit of pressure?
The SI unit of pressure is the pascal (Pa). 1 Pa = 1 N/m².
3. If you press a thumbtack into a wall, why does the point pierce the wall more easily than the blunt end?
Pressure increases when the force acts on a smaller area. The sharp point concentrates the force, producing higher pressure that pierces the wall.
4. Which of these statements about pressure in a liquid is true?
Hydrostatic pressure increases with depth according to p = p0 + ρgh, so deeper points have greater pressure.
5. Which expression gives the increase in pressure in a liquid due to a depth h below the surface?
The hydrostatic pressure contribution from a column of liquid of depth h is ρgh.
6. If two containers of different shapes are connected and filled with the same liquid, what is true about the pressure at the same level in both containers?
In connected vessels with the same fluid, pressure at the same horizontal level is equal regardless of the vessel shape (hydrostatic principle).
7. What does Pascal's principle state about pressure in a confined fluid?
Pascal's principle says that any applied pressure change in an enclosed fluid is transmitted equally throughout the fluid, which is the basis of hydraulic machines.
8. A small piston of area 0.02 m² is pushed with a force of 100 N in a hydraulic system. If the large piston has area 0.5 m², what upward force does the large piston produce (assuming ideal fluid)?
Pressure is the same: p = 100 N / 0.02 m² = 5000 Pa. Force on large piston = p × 0.5 m² = 5000 × 0.5 = 2500 N.
9. Atmospheric pressure at sea level is about:
Standard atmospheric pressure at sea level is approximately 101325 Pa, often rounded to 101300 Pa or 101.3 kPa.
10. Which instrument is commonly used to measure atmospheric pressure?
A barometer measures atmospheric pressure, often using a mercury column or an aneroid capsule.
11. Why does a suction pump work when you draw water up by lowering the pressure above it?
Reducing pressure above the water creates a pressure difference; atmospheric pressure on the reservoir pushes the water up into the lower-pressure area.
12. If a U-tube manometer shows a difference in liquid column height h, the pressure difference between the two sides equals:
The pressure difference supported by a column of liquid of height h is given by ρgh.
13. Which of these affects the hydrostatic pressure at a point inside a liquid?
Hydrostatic pressure at a point depends on depth and density (p = p0 + ρgh), not on container shape or liquid colour.
14. A closed container holds a gas and the temperature increases while volume stays constant. What happens to the gas pressure inside the container?
At constant volume, increasing temperature raises the average kinetic energy of gas molecules, increasing collision frequency and pressure (Gay-Lussac’s law).
15. Which of these statements explains why a wide flat shoe causes less damage to soft ground than a sharp high heel?
Lower pressure from a larger contact area reduces sinking and damage to soft ground.
16. Convert 2.5 kPa to pascals.
1 kPa = 1000 Pa, so 2.5 kPa = 2.5 × 1000 = 2500 Pa.
17. Why does a swimmer feel more pressure on their ears as they dive deeper underwater?
Hydrostatic pressure increases with depth (p increases by ρgh), so deeper water exerts greater pressure on the swimmer.
18. A column of mercury 760 mm high balances atmospheric pressure. If water is used instead of mercury, approximately how high would the water column be (density of water ≈ 1000 kg/m³, mercury ≈ 13600 kg/m³)?
Pressure is ρgh. For same pressure, h_water = h_Hg × (ρ_Hg/ρ_water) ≈ 0.760 m × (13600/1000) ≈ 10.3 m.
19. A tyre gauge shows the internal pressure of a car tyre as 220 kPa. This reading is most likely the pressure:
Tyre gauges usually show gauge pressure, the pressure above atmospheric pressure, measured in kPa.
20. If you cut a block into two pieces and apply the same force to the same face area on one piece, how does the pressure compare with the original block?
Pressure depends only on the force and area at the contact point (p = F/A); cutting the block does not change p if F and A are unchanged.
21. Which of these best describes why a gas exerts pressure on the walls of its container?
Gas pressure results from many molecular collisions with container walls, each transferring momentum and producing a force per unit area.
22. A boat floats because of buoyancy. Which pressure-related reason explains this?
Hydrostatic pressure increases with depth, so the pressure under the hull is higher than above, creating a net upward buoyant force.
23. In a laboratory, you apply the same force to two pistons of different areas in a closed fluid. If the small piston has area one-quarter of the larger one, how do the forces on the two pistons compare?
With equal pressure transmitted, force on a piston = pressure × area. If the large piston area is four times the small one, its force is four times larger.
24. Which unit is equivalent to 1 pascal?
By definition, 1 pascal equals one newton of force applied uniformly over one square metre (1 Pa = 1 N/m²).
25. When you squeeze a closed plastic bottle and release it quickly, air rushes back in. This happens because:
Squeezing and releasing changes internal pressure; when internal pressure is temporarily below atmospheric, outside air moves in to equalize the pressure.
26. During a practical, a pupil measures a force of 20 N acting on a plate of area 0.5 m². What is the pressure on the plate?
Pressure p = F/A = 20 N / 0.5 m² = 40 N/m² = 40 Pa.
27. Which of the following is NOT a factor that affects pressure at a given depth in a liquid?
Hydrostatic pressure depends on depth and density (and any layers above), but not on the container's shape.