Multiple Choice Questions (MCQs)
1) If the mass of Earth suddenly doubled, what would happen to the force of gravity between Earth and an object on its surface?
(a) It would double
(b) It would quadruple
(c) It would halve
(d) It would remain the same
Soln:
Answer is (a) It would double
Explanation:
The force of gravity is directly proportional to the mass of the planet. Hence, if Earth’s mass doubles, the gravitational force would also double.
2) What is the primary cause of ocean tides on Earth?
(a) The Sun’s gravity
(b) The Moon’s gravity
(c) Centrifugal force due to Earth’s rotation
(d) Changes in Earth’s magnetic field
Soln:
Answer is (b) The Moon’s gravity
Explanation:
Ocean tides are primarily caused by the gravitational pull of the Moon on Earth’s oceans.
3) An object weighs 20 N on the surface of the Earth. What would be its weight on a planet where the acceleration due to gravity is half that of Earth?
(a) 40 N
(b) 20 N
(c) 10 N
(d) 5 N
Soln:
Answer is (c) 10 N
Explanation:
Weight is directly proportional to the acceleration due to gravity. Halving the gravity would halve the weight.
4) Which principle explains why ships float on water?
(a) Pascal’s Principle
(b) Archimedes’ Principle
(c) Newton’s First Law of Motion
(d) Bernoulli’s Principle
Soln:
Answer is (b) Archimedes’ Principle
Explanation:
Archimedes’ Principle states that the buoyant force on an object submerged in a fluid is equal to the weight of the fluid displaced by the object, explaining why ships float.
5) What happens to the atmospheric pressure as we move upwards from Earth’s surface?
(a) It increases
(b) It decreases
(c) It remains constant
(d) It first decreases then increases
Soln:
Answer is (b) It decreases
Explanation:
Atmospheric pressure decreases with altitude as the density of air molecules decreases.
6) The value of acceleration due to gravity (g) is lower at the equator than at the poles. This is because:
(a) The equator is farther from the center of the Earth
(b) The rotation of Earth is faster at the equator
(c) The equator receives more sunlight
(d) Both (a) and (b)
Soln:
Answer is (d) Both (a) and (b)
Explanation:
The equator’s distance from the center of the Earth and the centrifugal force due to Earth’s rotation contribute to the lower value of g.
7) Which of the following statements is true regarding pressure in a fluid at rest?
(a) Pressure increases with depth
(b) Pressure decreases with depth
(c) Pressure is independent of depth
(d) Pressure is zero at all depths
Soln:
Answer is (a) Pressure increases with depth
Explanation:
In a fluid at rest, pressure increases linearly with depth due to the weight of the fluid above.
8) If the radius of the Earth were to shrink by half, keeping its mass constant, the acceleration due to gravity on the surface would:
(a) decrease by a factor of four
(b) decrease by half
(c) increase by a factor of four
(d) remain the same
Soln:
Answer is (c) increase by a factor of four
Explanation:
Since acceleration due to gravity is inversely proportional to the square of the radius, if the radius halves, gravity increases by a factor of four.
9) Which of the following is a unit of pressure?
(a) Newton
(b) Pascal
(c) Joule
(d) Watt
Soln:
Answer is (b) Pascal
Explanation:
Pascal is the SI unit of pressure, defined as one newton per square meter.
10) When a body is partially submerged in a fluid, it experiences an upward force. This is known as:
(a) Gravitational force
(b) Buoyant force
(c) Centripetal force
(d) Frictional force
Soln:
Answer is (b) Buoyant force
Explanation:
The buoyant force is the upward force exerted by a fluid that opposes the weight of an immersed object.
11) Which of the following factors does not affect the pressure exerted by a liquid?
(a) Depth of the liquid
(b) Density of the liquid
(c) Acceleration due to gravity
(d) Color of the liquid
Soln:
Answer is (d) Color of the liquid
Explanation:
The color of a liquid has no effect on the pressure it exerts; pressure depends on depth, density, and gravity.
12) What is the relation between density (ρ) and relative density (R.D)?
(a) ρ = R.D
(b) ρ = R.D × Density of water
(c) R.D = ρ × Density of water
(d) R.D = ρ / Density of water
Soln:
Answer is (d) R.D = ρ / Density of water
Explanation:
Relative density is the ratio of the density of a substance to the density of a reference substance (usually water).
13) A satellite in orbit around Earth experiences:
(a) Zero gravitational force
(b) Constant gravitational force
(c) Decreasing gravitational force with time
(d) Increasing gravitational force with time
Soln:
Answer is (b) Constant gravitational force
Explanation:
A satellite in orbit experiences a nearly constant gravitational force, which keeps it in orbit.
14) If the mass of the Earth were to increase with no change in radius, your weight would:
(a) Increase
(b) Decrease
(c) Remain the same
(d) Initially increase, then decrease
Soln:
Answer is (a) Increase
Explanation:
Weight is directly proportional to the mass of the Earth; an increase in Earth’s mass would result in an increase in weight.
15) Archimedes’ principle states that the buoyant force on a submerged object is equal to:
(a) The weight of the object
(b) The weight of the fluid displaced
(c) The volume of the fluid displaced
(d) The mass of the fluid displaced
Soln:
Answer is (b) The weight of the fluid displaced
Explanation:
Archimedes’ principle states that the buoyant force on a submerged object is equal to the weight of the fluid that the object displaces.
16) A balloon filled with helium gas floats in air because:
(a) Helium is lighter than air
(b) Helium is heavier than air
(c) The balloon is waterproof
(d) The balloon is colorless
Soln:
Answer is (a) Helium is lighter than air
Explanation:
Helium has a lower density compared to air, which makes the balloon buoyant and allows it to float.
17) What is the main reason for weightlessness experienced by astronauts in orbit?
(a) Absence of gravity in space
(b) Orbiting Earth at a very high speed
(c) The gravitational force is balanced by the centrifugal force
(d) Gravity is only a theory and not real
Soln:
Answer is (c) The gravitational force is balanced by the centrifugal force
Explanation:
Astronauts feel weightless in orbit because the gravitational pull is balanced by the centrifugal force due to their orbital motion, creating a state of free fall.
18) The pressure at a certain depth in a liquid is determined by:
(a) The type of liquid only
(b) The depth of the liquid and the gravitational force
(c) The container shape
(d) The surface area of the liquid
Soln:
Answer is (b) The depth of the liquid and the gravitational force
Explanation:
Pressure at a certain depth in a liquid depends on the depth of the liquid and the gravitational force acting on it.
19) If two objects, one heavy and one light, are dropped from the same height in a vacuum, they will:
(a) Fall at different rates, with the heavier object hitting first
(b) Fall at the same rate and hit the ground simultaneously
(c) Float and not fall
(d) Fall in slow motion
Soln:
Answer is (b) Fall at the same rate and hit the ground simultaneously
Explanation:
In a vacuum, without air resistance, objects fall at the same rate regardless of their mass.
20) The Universal Law of Gravitation applies to:
(a) Objects on Earth only
(b) Celestial bodies only
(c) Both objects on Earth and celestial bodies
(d) Objects in water
Soln:
Answer is (c) Both objects on Earth and celestial bodies
Explanation:
The Universal Law of Gravitation applies universally to all objects, whether on Earth or in celestial space.
21) When a ship moves from a river into the sea, it:
(a) Sinks slightly
(b) Rises slightly
(c) Remains at the same level
(d) Changes color
Soln:
Answer is (b) Rises slightly
Explanation:
When a ship moves from a river (freshwater) to the sea (saltwater), it rises slightly due to the higher density of seawater, which increases buoyancy.
22) The density of an object is defined as:
(a) The mass per unit volume of the object
(b) The volume per unit mass of the object
(c) The weight per unit volume of the object
(d) The height per unit mass of the object
Soln:
Answer is (a) The mass per unit volume of the object
Explanation:
Density is defined as the mass per unit volume of a substance.
23) Which factor affects the gravitational force between two objects the most?
(a) Color of the objects
(b) Surface area of the objects
(c) Distance between the objects
(d) Temperature of the objects
Soln:
Answer is (c) Distance between the objects
Explanation:
The gravitational force between two objects is most significantly affected by the distance between them, as it varies inversely with the square of the distance.
24) What happens to the buoyant force as the depth of an object submerged in a fluid increases?
(a) It increases
(b) It decreases
(c) It remains the same
(d) It first increases then decreases
Soln:
Answer is (c) It remains the same
Explanation:
The buoyant force depends on the volume of fluid displaced and not on the depth at which the object is submerged.
25) A body is fully submerged in a fluid. The force exerted by the fluid on the bottom of the body is:
(a) Equal to the weight of the body
(b) Less than the weight of the body
(c) More than the weight of the body
(d) Equal to the buoyant force
Soln:
Answer is (a) Equal to the weight of the body
Explanation:
When a body is fully submerged, the force exerted by the fluid on its bottom is equal to the weight of the body.
26) What would happen to your weight if you went to the top of a high mountain?
(a) It would decrease
(b) It would increase
(c) It would remain the same
(d) It would fluctuate
Soln:
Answer is (a) It would decrease
Explanation:
Your weight would slightly decrease due to a small reduction in the Earth’s gravitational pull at higher altitudes.
27) The pressure exerted by a fluid at a specific point:
(a) Acts only vertically downwards
(b) Acts only vertically upwards
(c) Acts in all directions
(d) Is unpredictable
Soln:
Answer is (c) Acts in all directions
Explanation:
Fluid pressure at a point acts equally in all directions.
28) If Earth’s gravitational force suddenly vanished, how would an object’s mass and weight be affected?
(a) Both mass and weight would become zero
(b) Mass would become zero, but weight would remain the same
(c) Mass would remain the same, but weight would become zero
(d) Both mass and weight would remain the same
Soln:
Answer is (c) Mass would remain the same, but weight would become zero
Explanation:
Mass is an intrinsic property and would remain the same, but weight, which depends on gravity, would become zero.
29) The gravitational force between two objects is directly proportional to:
(a) The sum of their masses
(b) The difference in their masses
(c) The product of their masses
(d) The ratio of their masses
Soln:
Answer is (c) The product of their masses
Explanation:
The gravitational force is directly proportional to the product of the masses of the two objects.
30) In a hydraulic lift system, the principle involved is:
(a) Pascal’s principle
(b) Archimedes’ principle
(c) Newton’s first law of motion
(d) Bernoulli’s principle
Soln:
Answer is (a) Pascal’s principle
Explanation:
A hydraulic lift operates based on Pascal’s principle, which states that pressure exerted anywhere in a confined fluid is transmitted equally in all directions.
31) If the density of a substance is greater than the density of water, the substance will:
(a) Float on water
(b) Sink in water
(c) Dissolve in water
(d) Neither float nor sink
Soln:
Answer is (b) Sink in water
Explanation:
A substance denser than water will sink when placed in water.
32) When an object is immersed in a fluid, it displaces a volume of fluid equal to:
(a) Its own volume
(b) Half of its volume
(c) Twice its volume
(d) Its weight
Soln:
Answer is (a) Its own volume
Explanation:
According to Archimedes’ principle, an object immersed in a fluid displaces a volume of fluid equal to its own volume.
33) The acceleration due to gravity (g) is least at:
(a) Sea level
(b) The top of a mountain
(c) The North Pole
(d) The Equator
Soln:
Answer is (d) The Equator
Explanation:
The value of ‘g’ is least at the Equator due to the bulging of the Earth at the equator and the centrifugal force due to Earth’s rotation.
34) Which of the following represents the correct relationship between atmospheric pressure (P), density of air (ρ), and height (h) from the Earth’s surface?
(a) P ∝ ρh
(b) P ∝ ρ/h
(c) P ∝ h/ρ
(d) P ∝ 1/(ρh)
Soln:
Answer is (a) P ∝ ρh
Explanation:
Atmospheric pressure is directly proportional to the density of air and the height from the Earth’s surface.
35) If you are in a spaceship far from any celestial body, what would be your weight?
(a) It would be zero
(b) It would be the same as on Earth
(c) It would be less than on Earth
(d) It would be more than on Earth
Soln:
Answer is (a) It would be zero
Explanation:
Weight is the force of gravity on an object. In space, far from any celestial body, this force is virtually absent, making your weight zero.
36) A block of wood is floating in water with half of its volume submerged. This indicates that the density of the wood is:
(a) Equal to the density of water
(b) Half the density of water
(c) Twice the density of water
(d) Four times the density of water
Soln:
Answer is (b) Half the density of water
Explanation:
Since half of its volume is submerged, it indicates that the density of the wood is half that of water.
37) What happens to the gravitational force between two objects if the distance between them is halved?
(a) It becomes four times greater
(b) It becomes half
(c) It becomes twice
(d) It remains the same
Soln:
Answer is (a) It becomes four times greater
Explanation:
Gravitational force is inversely proportional to the square of the distance. If the distance is halved, the force becomes four times greater.
38) If you weigh 600 N on the Earth, what would be your weight on a planet where the acceleration due to gravity is twice that of Earth?
(a) 300 N
(b) 600 N
(c) 1200 N
(d) 2400 N
Soln:
Answer is (c) 1200 N
Explanation:
Weight is directly proportional to the acceleration due to gravity. If gravity is doubled, weight also doubles.
39) In a fluid, as depth increases, which of the following also increases?
(a) Density
(b) Temperature
(c) Pressure
(d) Viscosity
Soln:
Answer is (c) Pressure
Explanation:
Pressure in a fluid increases with depth due to the weight of the fluid above.
40) The principle used in a hydraulic brake system is:
(a) Newton’s First Law of Motion
(b) Archimedes’ Principle
(c) Pascal’s Principle
(d) Bernoulli’s Principle
Soln:
Answer is (c) Pascal’s Principle
Explanation:
Hydraulic brakes operate on Pascal’s Principle, which states that pressure applied to a confined fluid is transmitted undiminished throughout the fluid.