Understanding the difference between mass and weight is crucial for students preparing for JEE, NEET, and CBSE Board Class 11 exams. Though often used interchangeably, mass and weight are distinct physical quantities. This article provides a clear differentiation, along with multiple-choice questions (MCQs) and FAQs to solidify your understanding.
Difference Between Mass & Weight
Property
Mass
Weight
Definition
The amount of matter in a body
The force exerted by gravity on an object
SI Unit
Kilogram (kg)
Newton (N)
Dependence
Constant everywhere
Varies with gravity
Measured By
Balance
Spring Balance
Nature
Scalar quantity
Vector quantity
FAQs on Mass & Weight
Q1: Why is mass constant but weight varies?
A: Mass is an intrinsic property of an object and remains unchanged regardless of location. Weight depends on gravitational pull, which varies from place to place (e.g., it is lower on the Moon than on Earth).
Q2: Can weight be zero?
A: Yes, in space or a zero-gravity environment, an object experiences weightlessness, meaning its weight becomes zero, but its mass remains the same.
Q3: Which instrument is used to measure mass and weight?
A: Mass is measured using a balance, whereas weight is measured using a spring balance.
Q4: Is weight a vector or scalar quantity?
A: Weight is a vector quantity as it has both magnitude and direction (acting towards the center of the gravitational pull).
Q5: How does weight change on different planets?
A: Weight depends on gravitational acceleration. Since different planets have different gravity values, an object’s weight changes accordingly.
MCQs on Mass & Weight
1. What is the SI unit of mass?
a) Newton
b) Kilogram
c) Joule
d) Pascal Answer: b) Kilogram Explanation: The SI unit of mass is the kilogram (kg), while Newton (N) is the unit of force.
2. Which of the following is a scalar quantity?
a) Force
b) Velocity
c) Weight
d) Mass Answer: d) Mass Explanation: Mass is a scalar quantity because it has magnitude only, while weight is a vector as it has both magnitude and direction.
3. What happens to an object’s weight if it is taken to the Moon?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero Answer: b) Decreases Explanation: The Moon’s gravity is about 1/6th that of Earth, so the object’s weight decreases, but its mass remains the same.
4. Which instrument is used to measure weight?
a) Spring balance
b) Beam balance
c) Vernier calipers
d) Barometer Answer: a) Spring balance Explanation: Spring balance measures weight as it responds to the force of gravity.
5. The weight of an object on Earth is 600N. What would be its weight on the Moon? (Given Moon’s gravity is 1/6th of Earth’s gravity)
a) 600N
b) 100N
c) 3600N
d) 60N Answer: b) 100N Explanation: Weight on Moon = (1/6) × Weight on Earth = (1/6) × 600N = 100N.
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{ q: “What is the SI unit of mass?”, options: [“Newton”, “Kilogram”, “Joule”, “Watt”], answer: 1, explanation: “The SI unit of mass is the kilogram (kg).” },
{ q: “What is the SI unit of weight?”, options: [“Newton”, “Kilogram”, “Gram”, “Meter”], answer: 0, explanation: “Weight is a force and its SI unit is Newton (N).” },
{ q: “What is the formula for weight?”, options: [“W = mg”, “W = m/g”, “W = g/m”, “W = m + g”], answer: 0, explanation: “Weight is given by W = mg, where g is acceleration due to gravity.” },
{ q: “How does mass change on the Moon compared to Earth?”, options: [“Increases”, “Decreases”, “Remains the same”, “Becomes zero”], answer: 2, explanation: “Mass remains the same regardless of location.” },
{ q: “How does weight change on the Moon compared to Earth?”, options: [“Increases”, “Decreases”, “Remains the same”, “Doubles”], answer: 1, explanation: “Weight decreases because the Moon’s gravity is weaker than Earth’s.” },
{ q: “Which quantity is a scalar?”, options: [“Weight”, “Force”, “Mass”, “Acceleration”], answer: 2, explanation: “Mass is a scalar quantity, while weight is a vector.” },
{ q: “What is the approximate value of g on Earth?”, options: [“9.8 m/s²”, “6.67 m/s²”, “10.5 m/s²”, “1.6 m/s²”], answer: 0, explanation: “The acceleration due to gravity on Earth is approximately 9.8 m/s².” },
{ q: “If an object’s mass is 10 kg, what is its weight on Earth?”, options: [“10 N”, “98 N”, “9.8 N”, “100 N”], answer: 1, explanation: “Using W = mg, W = 10 × 9.8 = 98 N.” },
{ q: “Does mass depend on gravity?”, options: [“Yes”, “No”, “Sometimes”, “Only in space”], answer: 1, explanation: “Mass is an intrinsic property and does not depend on gravity.” },
{ q: “Which of the following is an example of weight?”, options: [“The amount of matter in an object”, “The force pulling an object downward”, “The space occupied by an object”, “The object’s resistance to motion”], answer: 1, explanation: “Weight is the force exerted by gravity on an object.” }
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