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Q1. The weight of a body on moon is less because
The weight of a body on the Moon is less because the Moon has less mass than the Earth. The gravitational force exerted by a body depends on its mass. Since the Moon’s mass is only about 1/81 of Earth’s mass, its gravitational pull is much weaker. The presence or absence of water, air, or rotation speed does not significantly affect the gravitational force. The weaker gravity on the Moon is due to its smaller mass.
Q2. Which remains constant everywhere?
Mass is the amount of matter in an object and remains constant everywhere in the universe. Whether an object is on Earth, on the Moon, or in deep space, its mass does not change. Weight depends on gravity, which varies from place to place. Force also depends on the situation. Gravity (g) changes with location. So mass is the only quantity that remains constant everywhere.
Q3. An astronaut feels weightless because
An astronaut in orbit around the Earth feels weightless because both the astronaut and the spacecraft are in free fall towards the Earth. They are falling together with the same acceleration, so there is no normal force from the floor to push against. This creates the sensation of weightlessness. Gravity is still present—it is what keeps the spacecraft in orbit. The astronaut’s mass is also unchanged. Weightlessness is actually a state of continuous free fall.
Q4. Weight is maximum at
Weight is maximum at the poles because the value of g is slightly greater at the poles than at the equator. This is because the Earth is not a perfect sphere—it bulges at the equator and is flattened at the poles. So the distance from the Earth’s centre is smaller at the poles, making g slightly larger. Additionally, the centrifugal effect of Earth’s rotation is zero at the poles. At the centre of the Earth, g would be zero, so weight would be zero there.
Q5. Weight always acts along
Weight always acts along the radius towards the centre of the Earth. This means it acts vertically downward along the line joining the object to the Earth’s centre. The direction of weight is always towards the centre of the attracting body. This is why objects fall straight down when dropped—they are being pulled towards the centre of the Earth.
Q6. Gravitational force depends on
According to Newton’s universal law of gravitation, the gravitational force between two objects depends on the product of their masses and the square of the distance between their centres. The formula is F = GMm/d². This means both mass and distance are important. The force is directly proportional to the product of masses and inversely proportional to the square of the distance.
Q7. The gravitational force is always
Gravitational force is always attractive. It pulls objects towards each other. Unlike electric or magnetic forces, which can be either attractive or repulsive, gravity only attracts. This is why planets are pulled towards the Sun, objects fall towards the Earth, and all objects in the universe attract each other.
Q8. Weight depends directly on
Weight W = mg is directly proportional to mass. At a given location where g is constant, if mass increases, weight increases proportionally. If mass doubles, weight doubles. Weight does not depend on area, density, or velocity directly. For example, a heavier object has more weight, regardless of its shape or density.
Q9. The value of g on Earth is approximately
The standard value of acceleration due to gravity on Earth’s surface is approximately 9.8 m/s². This value varies slightly depending on location, but 9.8 m/s² is the average value used in most calculations. Sometimes 10 m/s² is used as an approximation for simplicity in school-level problems.
Q10. Weight of an object depends on
Weight depends on the location because the acceleration due to gravity g varies from place to place. On different planets, on the Moon, or at different altitudes on Earth, g changes. Since W = mg, the weight changes when the location changes. Temperature, shape, and colour do not affect weight. An object’s weight is determined by its mass and the gravitational field at that location.
Q11. Weight is always directed
Weight is a force that always acts towards the centre of the Earth. This is because gravitational force pulls objects towards the centre of the attracting body. The direction is along the radius of the Earth, which is what we call vertically downward. This consistent direction is why objects fall down and why weight is used as a vertical force in many applications.
Q12. Weight is the result of interaction between
Weight is the gravitational force between an object and the Earth. It results from the interaction between the mass of the object and the mass of the Earth. This is described by Newton’s law of gravitation: F = GMm/d², where M is the mass of the Earth and m is the mass of the object. The interaction between two charges produces electric force, and between two magnets produces magnetic force.
Q13. Weight of an object depends on
Weight depends on two factors: the mass of the object and the acceleration due to gravity at its location. The formula W = mg makes this clear. If either mass or gravity changes, the weight changes. Shape, volume, and speed do not affect weight. For example, a 10 kg object has a weight of 98 N on Earth (g = 9.8) but only 16 N on the Moon (g = 1.6).
Q14. If g increases, weight will
Since W = mg, weight is directly proportional to g. If g increases, weight also increases. For example, if you go to a planet with stronger gravity, you would weigh more. If you go to a place with weaker gravity, you would weigh less. This is why the same object weighs more at the poles (where g is slightly higher) than at the equator.
Q15. The SI unit of g is
The SI unit of acceleration due to gravity g is metres per second squared (m/s²). This is the same as the unit of acceleration. It tells us how much the velocity of a falling object increases per second. For example, g = 9.8 m/s² means the speed increases by 9.8 m/s every second. Newton (N) is the unit of force, m/s is the unit of speed, and kg is the unit of mass.
Q16. Which instrument measures weight?
A spring balance measures weight. It works on the principle that the force of gravity stretches a spring, and the amount of stretch is proportional to the weight. A beam balance, on the other hand, is used to measure mass by comparing the object with standard masses. A thermometer measures temperature, and a meter scale measures length.
Q17. Which is a scalar quantity?
Mass is a scalar quantity because it has only magnitude and no direction. Scalar quantities are fully described by a number and a unit. Weight, force, and velocity are vector quantities because they have both magnitude and direction. Mass is the amount of matter in an object and does not have a direction associated with it.
Q18. The force responsible for weight is
Weight is the gravitational force exerted by the Earth on an object. It is the force of attraction between the object and the Earth. This force is due to gravity. Electrostatic force is between charges, magnetic force is between magnets, and nuclear force acts within the nucleus of an atom. So the correct answer is gravitational force.
Q19. An object weighs 0 N when
Weight W = mg. For weight to be zero, either mass m must be zero (which is impossible for any real object) or gravity g must be zero. In deep space far from any massive object, gravity is negligible, so weight is zero. At the centre of the Earth, g is zero, so weight would be zero there as well. So weight is zero when gravity is zero.
Q20. The gravitational force on an object is also called
The gravitational force exerted by the Earth on an object is called its weight. Weight is the downward force due to gravity. Friction opposes motion, thrust is a pushing force, and pressure is force per unit area. So the gravitational force on an object is correctly called weight.
Q21. Which instrument measures mass?
A beam balance is used to measure mass. It compares the mass of an object with known standard masses. It works on the principle of balancing weights. A spring balance measures weight, a barometer measures atmospheric pressure, and a speedometer measures speed. A beam balance would give the same reading on the Moon as on Earth because mass does not change.
Q22. The gravitational attraction is strongest at
The gravitational attraction is strongest at the Earth’s poles because g is slightly greater at the poles. This is due to the Earth being slightly flattened at the poles (so the distance to the centre is smaller) and the absence of the centrifugal effect of rotation. At the centre of the Earth, g would be zero. The Sun has stronger gravity overall, but the question likely refers to places on Earth.
Q23. If mass is zero, weight will be
Weight W = mg. If mass m = 0, then W = 0 × g = 0. So weight would be zero. This is a theoretical case because all real objects have mass. However, this shows that weight depends on mass, and if there is no mass, there is no weight.
Q24. Gravity acts on
Gravity acts on all objects that have mass. It does not matter whether the object is living or non-living, heavy or light, magnetic or non-magnetic. Everything with mass experiences gravitational attraction. This is why the universal law of gravitation is called universal—it applies to all objects in the universe.
Q25. Which quantity remains unchanged on Earth and Moon?
Mass remains unchanged on Earth and the Moon because it is an intrinsic property of matter. Weight changes because the Moon has weaker gravity. Force depends on the situation, and gravity (g) is different on the Moon. So mass is the only quantity that is the same on both Earth and the Moon.
Q26. Weight of an object decreases when
Since W = mg, weight decreases when g decreases. This happens when you move to a location with weaker gravity, such as the Moon or higher altitudes. Mass does not change, so weight decreases only when gravity decreases. Volume and density do not affect weight directly.
Q27. Weight is proportional to
Weight is proportional to the product of mass m and acceleration due to gravity g. The formula W = mg shows this directly. Both mass and gravity are factors. For a fixed location (g constant), weight is proportional to mass. For a fixed mass, weight is proportional to g.
Q28. Weight changes with
Weight changes with place because g changes with location. Colour, volume, and shape do not affect weight. An object will have different weights on different planets or at different altitudes because the gravitational field changes. This is why we say weight depends on location.
Q29. Weight of an object is caused due to
Weight is caused by gravitation. It is the gravitational force exerted by the Earth on an object. Magnetism, friction, and pressure are different types of forces. Weight is specifically the force of gravity, so gravitation is the correct answer.
Q30. Gravity on the moon is about
The acceleration due to gravity on the Moon is about one-sixth of that on Earth. The Moon’s gravity is 1.6 m/s² compared to Earth’s 9.8 m/s². This means objects weigh about one-sixth as much on the Moon as they do on Earth.
Q31. Weight is absent in
Weight is not absent in free fall—it is still present. However, the sensation of weight is absent because the object is in free fall and there is no normal force. In free fall, the object is accelerating downward with g, and there is no support force from the floor, so weight is not felt. In reality, the weight still exists, but it appears to be zero to the falling object.
Q32. The relation W = m × g shows weight depends on
The relation W = mg shows that weight depends on mass (m) and acceleration due to gravity (g). Density, size, and shape do not directly enter into the formula. Weight is a force that is determined by these two factors only.
Q33. Which is a vector quantity?
Weight is a vector quantity because it has both magnitude and direction. Mass, time, and density are scalar quantities—they have only magnitude. Weight acts downward towards the centre of the Earth, giving it a direction. This is what makes it a vector.
Q34. An object taken from Earth to Moon will have
Mass is a property of the object and does not change with location. So the mass remains the same on both Earth and the Moon. However, the Moon has weaker gravity, so the weight is less on the Moon. This is why astronauts feel lighter on the Moon but their mass is unchanged.
Q35. If g becomes zero, the weight of an object will be
If g = 0, then W = m × 0 = 0. So weight becomes zero. This would happen at the centre of the Earth or in deep space far from any massive object. This shows that weight depends on gravity, and without gravity, there is no weight.
Q36. An object’s weight becomes less when moved from
When an object is moved from Earth to the Moon, its weight decreases because the Moon has weaker gravity. Moving from the pole to the centre of the Earth would reduce weight to zero because g is zero at the centre. But the most common scenario is moving from Earth to the Moon, where weight becomes one-sixth of the Earth weight.
Q37. Weight is the force with which Earth
Weight is the attractive force of the Earth on an object. The Earth pulls objects towards its centre through gravity. It does not repel, push (except through normal force in contact situations), or support (except indirectly). The fundamental nature of weight is attraction due to gravity.
Q38. If mass of an object is doubled at the same place, its weight becomes
At the same place, g is constant. So W = mg. If mass doubles, weight also doubles. For example, if a 5 kg object has a weight of 49 N, a 10 kg object has a weight of 98 N at the same location. Weight is directly proportional to mass.
Q39. Gravity on Earth acts
Gravity on Earth acts downwards, towards the centre of the Earth. This is the direction that objects fall when dropped. “Downwards” means along the vertical direction towards the Earth’s centre. Gravity does not act upwards, sideways, or outwards.
Q40. The weight of an object on Earth is due to attraction between
The weight of an object on Earth is the force of attraction between the object and the Earth. It is the Earth’s gravity that pulls the object downward. The Moon, air, and Sun also exert gravitational forces, but they are negligible compared to the Earth’s gravity for objects on Earth.
Q41. At the centre of Earth, the weight of an object is
At the centre of the Earth, the gravitational forces from all directions cancel each other out. Since the object is pulled equally in all directions, the net gravitational force is zero. Therefore, the weight of the object at the centre of the Earth is zero.
Q42. Weight of an object increases if
Since W = mg, if g increases, weight increases. If mass decreases, weight decreases. Radius and distance affect g, but directly, weight increases when g increases. This happens at the poles or on a planet with stronger gravity.
Q43. Weight can be zero even when mass is
Weight can be zero even when mass is present. This happens when g = 0, such as at the centre of the Earth or in deep space. Weight is not an inherent property of matter; it depends on the gravitational field. So an object with mass can have zero weight if there is no gravity acting on it.
Q44. Which statement is correct?
Mass is constant because it is an intrinsic property of matter. Weight is not constant—it changes with location. Gravity is not the same everywhere—it varies. Mass does not change with place. So the correct statement is that mass is constant.
Q45. Weight of an object in free fall is
In free fall, the object appears to be weightless because there is no normal force acting on it. Although the weight (mg) is still present, it is not felt because both the object and the measuring scale are falling together. This is why we say the apparent weight in free fall is zero.
Q46. Which factor does NOT affect weight?
Weight is affected by mass and gravity, and therefore by location (since g varies). Colour does not affect weight. An object’s weight does not depend on what colour it is—it only depends on its mass and the gravitational field.
Q47. Weight is measured in
Weight is a force, so it is measured in newtons (N). Mass is measured in kilograms (kg), length in metres (m), and time in seconds (s). It is important to distinguish between mass (kg) and weight (N). For example, a 10 kg object weighs about 98 N on Earth.
Q48. Weight of an object on the Moon compared to Earth is
The Moon has weaker gravity than Earth, so the weight of an object on the Moon is less than its weight on Earth. Specifically, the Moon’s gravity is about one-sixth of Earth’s, so the weight is also one-sixth. Mass remains the same, but weight is less.
Q49. The gravitational pull of Moon is weaker because
The Moon’s gravitational pull is weaker because it has less mass (it is smaller). The gravitational force depends on mass. The Moon’s smaller mass means its gravitational field is weaker than Earth’s. Distance, rotation, and temperature do not significantly affect the gravitational pull.
Q50. Weight of an object can never be
Weight is a force that always acts downward towards the centre of the Earth. It is always positive in magnitude (mg, where m and g are positive). Weight can be zero if gravity is zero, but it can never be negative because negative weight would mean a force acting upward, which gravity never does. So weight can never be negative.