1. A sharp knife cuts vegetables more easily than a blunt knife because a sharp knife:
(A) Applies less force
(B) Has a smaller contact area and produces greater pressure
(C) Has greater mass
(D) Produces less pressure
Answer: (B) Has a smaller contact area and produces greater pressure
Explanation: Pressure is force per unit area. For the same force, a smaller area produces greater pressure.
2. A sharp needle can easily penetrate cloth because:
(A) It has a large surface area
(B) It produces low pressure
(C) Its pointed tip has a very small area
(D) It has very little mass
Answer: (C) Its pointed tip has a very small area
Explanation: A small contact area produces high pressure for the same applied force.
3. School bags have broad straps mainly to:
(A) Increase pressure on the shoulders
(B) Reduce pressure on the shoulders
(C) Increase the weight of the bag
(D) Increase friction
Answer: (B) Reduce pressure on the shoulders
Explanation: Broad straps increase the contact area, thereby reducing pressure.
4. Camel’s feet are broad because they:
(A) Increase pressure on sand
(B) Reduce pressure on sand
(C) Increase the camel’s weight
(D) Increase friction with air
Answer: (B) Reduce pressure on sand
Explanation: Broad feet distribute the camel’s weight over a larger area, preventing it from sinking deeply into sand.
5. Tractor tyres are made wider than ordinary vehicle tyres mainly to:
(A) Increase pressure on the soil
(B) Reduce pressure on the soil
(C) Increase the weight of the tractor
(D) Increase engine power
Answer: (B) Reduce pressure on the soil
6. A person wearing high-heeled shoes sinks more easily into soft ground because:
(A) High heels have a large contact area
(B) High heels produce greater pressure due to their small contact area
(C) The person’s weight increases
(D) Gravity becomes stronger
Answer: (B) High heels produce greater pressure due to their small contact area
7. Pressure exerted by a force is given by:
(A) P = F × A
(B) P = F/A
(C) P = A/F
(D) P = F + A
Answer: (B) P = F/A
8. A force of 100 N acts perpendicular to an area of 2 m². What pressure is produced?
(A) 25 Pa
(B) 50 Pa
(C) 100 Pa
(D) 200 Pa
Answer: (B) 50 Pa
Explanation: Pressure = Force/Area = 100/2 = 50 Pa.
9. If the same force is applied over a smaller area, the pressure:
(A) Decreases
(B) Increases
(C) Remains unchanged
(D) Becomes zero
Answer: (B) Increases
10. If the area of contact is doubled while the applied force remains constant, the pressure becomes:
(A) Double
(B) Half
(C) Four times
(D) Unchanged
Answer: (B) Half
11. The SI unit of pressure is:
(A) Newton
(B) Joule
(C) Pascal
(D) Watt
Answer: (C) Pascal
12. One Pascal is equal to:
(A) 1 N/m²
(B) 1 N × m²
(C) 1 kg/m²
(D) 1 J/m²
Answer: (A) 1 N/m²
13. Hydraulic lifts used in automobile service stations work mainly on:
(A) Archimedes’ principle
(B) Pascal’s law
(C) Newton’s first law
(D) Bernoulli’s principle
Answer: (B) Pascal’s law
14. The working principle of hydraulic brakes is:
(A) Pascal’s law
(B) Archimedes’ principle
(C) Newton’s law of gravitation
(D) Law of conservation of mass
Answer: (A) Pascal’s law
15. Pascal’s law states that pressure applied to an enclosed fluid is:
(A) Lost completely
(B) Transmitted equally in all directions
(C) Transmitted only downward
(D) Transmitted only upward
Answer: (B) Transmitted equally in all directions
16. In a hydraulic lift, a small force can lift a heavy load because:
(A) Pressure is transmitted through the confined fluid
(B) Gravity is eliminated
(C) The mass of the load decreases
(D) Friction becomes zero
Answer: (A) Pressure is transmitted through the confined fluid
17. A syringe works primarily because:
(A) Magnetic force acts on the liquid
(B) A pressure difference causes the liquid to move
(C) Gravity disappears inside the syringe
(D) The liquid becomes weightless
Answer: (B) A pressure difference causes the liquid to move
18. When the plunger of a syringe is pulled upward, the pressure inside the syringe:
(A) Increases greatly
(B) Decreases
(C) Remains exactly the same
(D) Becomes infinite
Answer: (B) Decreases
19. A person can drink liquid through a straw mainly because:
(A) The liquid is pulled upward by gravity
(B) Atmospheric pressure pushes the liquid upward
(C) The straw produces water pressure
(D) The liquid becomes lighter
Answer: (B) Atmospheric pressure pushes the liquid upward
20. When a person sucks air from a straw, the pressure inside the straw:
(A) Increases above atmospheric pressure
(B) Decreases below atmospheric pressure
(C) Becomes equal to zero
(D) Remains unchanged
Answer: (B) Decreases below atmospheric pressure
21. A suction cup sticks to a smooth wall mainly because:
(A) Magnetic attraction acts between the cup and wall
(B) Atmospheric pressure presses the cup against the wall
(C) Gravity pulls the cup upward
(D) Friction produces atmospheric pressure
Answer: (B) Atmospheric pressure presses the cup against the wall
22. Atmospheric pressure is caused primarily by:
(A) The weight of the atmosphere
(B) The weight of oceans
(C) Earth’s magnetic field
(D) Solar radiation alone
Answer: (A) The weight of the atmosphere
23. The pressure exerted by a liquid generally:
(A) Decreases with depth
(B) Increases with depth
(C) Remains the same at all depths
(D) Becomes zero at the bottom
Answer: (B) Increases with depth
24. Dam walls are made thicker at the bottom because:
(A) Water is colder at the bottom
(B) Water pressure increases with depth
(C) Gravity is absent at the top
(D) Water pressure decreases with depth
Answer: (B) Water pressure increases with depth
25. If two points are at different depths in the same liquid, the greater pressure is found at the:
(A) Higher point
(B) Lower point
(C) Surface only
(D) Same at both points
Answer: (B) Lower point
26. The principle responsible for the floating of ships is:
(A) Pascal’s law
(B) Archimedes’ principle
(C) Newton’s first law
(D) Ohm’s law
Answer: (B) Archimedes’ principle
27. According to Archimedes’ principle, the buoyant force acting on an immersed body is equal to:
(A) Weight of the body
(B) Weight of the displaced fluid
(C) Mass of the body
(D) Volume of the body
Answer: (B) Weight of the displaced fluid
28. A ship made of steel can float on water because:
(A) Steel is lighter than water
(B) The ship displaces enough water to produce sufficient buoyant force
(C) Gravity does not act on ships
(D) Steel has no weight when placed in water
Answer: (B) The ship displaces enough water to produce sufficient buoyant force
29. A submarine can dive and rise in water by changing its:
(A) Temperature
(B) Density
(C) Colour
(D) Magnetic field
Answer: (B) Density
30. A submarine dives when its ballast tanks are filled with water because:
(A) Its average density increases
(B) Its average density decreases
(C) Gravity stops acting on it
(D) Water loses its buoyancy
Answer: (A) Its average density increases
31. A submarine rises toward the surface when:
(A) Water is admitted into its ballast tanks
(B) Water is expelled and air is introduced into its ballast tanks
(C) Its mass is increased
(D) Its volume becomes zero
Answer: (B) Water is expelled and air is introduced into its ballast tanks
32. A hydrometer is an instrument used to measure:
(A) Atmospheric pressure
(B) Relative density of liquids
(C) Temperature
(D) Atmospheric humidity
Answer: (B) Relative density of liquids
33. A hydrometer works mainly on the principle of:
(A) Buoyancy
(B) Magnetism
(C) Thermal expansion
(D) Electromagnetic induction
Answer: (A) Buoyancy
34. A hydrometer floats higher in a liquid that is:
(A) Less dense
(B) More dense
(C) At a higher temperature only
(D) At lower pressure only
Answer: (B) More dense
35. A body floats in a liquid when:
(A) Its weight is greater than the buoyant force
(B) The buoyant force equals its weight
(C) Its density is always greater than the liquid
(D) There is no gravitational force
Answer: (B) The buoyant force equals its weight
36. A body will sink in a liquid if:
(A) Its average density is greater than that of the liquid
(B) Its average density is less than that of the liquid
(C) Buoyant force is greater than its weight
(D) Its weight is zero
Answer: (A) Its average density is greater than that of the liquid
37. Which of the following is correctly matched?
(A) Hydraulic lift — Pascal’s law
(B) Ship — Newton’s third law
(C) Hydrometer — Ohm’s law
(D) Syringe — Electromagnetic induction
Answer: (A) Hydraulic lift — Pascal’s law
38. Which of the following is incorrectly matched?
(A) Sharp knife — High pressure
(B) Broad bag strap — Low pressure
(C) Dam wall — Pressure increases with depth
(D) Ship — Pascal’s law
Answer: (D) Ship — Pascal’s law
39. A force of 200 N acts on an area of 4 m². The pressure exerted is:
(A) 25 Pa
(B) 50 Pa
(C) 100 Pa
(D) 800 Pa
Answer: (B) 50 Pa
Explanation: P = F/A = 200/4 = 50 Pa.
40. Which of the following applications is primarily associated with atmospheric pressure?
(A) Hydraulic lift
(B) Drinking through a straw
(C) Floating ship
(D) Hydrometer
Answer: (B) Drinking through a straw
Quick Revision: Pressure & Fluids
| Application | Principle |
|---|---|
| Sharp knife | Small area → high pressure |
| Sharp needle | Small area → high pressure |
| Broad school-bag straps | Large area → low pressure |
| Camel’s feet | Reduces pressure on sand |
| Broad tractor tyres | Reduces pressure on soil |
| High heels | Small area → high pressure |
| Hydraulic lift | Pascal’s law |
| Hydraulic brakes | Pascal’s law |
| Syringe | Pressure difference |
| Drinking through straw | Atmospheric pressure |
| Suction cup | Atmospheric pressure |
| Dam walls | Pressure increases with depth |
| Ship | Archimedes’ principle |
| Submarine | Buoyancy/density |
| Hydrometer | Buoyancy/relative density |