IGCSE Physics 1.3 Mass and Weight MCQs – 30 Practice Questions with Answers (Cambridge 0625)
Thirty original practice MCQs on Cambridge IGCSE Physics (0625) Section 1.3, Mass and Weight, written for Core and Supplement students. Every question has a worked answer, so you can check not just whether you were right, but why.
Formula recap: weight W = mg (weight in newtons, mass in kg, g in N/kg) and gravitational field strength g = W / m. Keep these handy, then test yourself below – full list on the IGCSE Physics Formula Sheet.
Mass vs Weight
Q1. What is the correct definition of the mass of an object?
- (A) The amount of matter in the object
- (B) The force of gravity acting on the object
- (C) The volume occupied by the object
- (D) The weight of the object measured in newtons
Show Answer
Answer: A – Mass is the amount of matter in an object and is measured in kilograms (kg). Weight (option B) is a force, not mass.
Q2. The weight of an object is best described as
- (A) a mass measured in kilograms
- (B) the gravitational force acting on the object
- (C) the density of the object
- (D) the amount of matter in the object
Show Answer
Answer: B – Weight is a force caused by gravity pulling on the object’s mass, so it is measured in newtons (N).
Q3. Which row gives the correct SI units for mass and for weight?
- (A) mass: newton, weight: kilogram
- (B) mass: kilogram, weight: kilogram
- (C) mass: kilogram, weight: newton
- (D) mass: newton, weight: newton
Show Answer
Answer: C – Mass is measured in kilograms (kg); weight is a force, so it is measured in newtons (N).
Q4. A 2 kg object is taken from the Earth to the Moon, where the gravitational field is weaker. What happens to its mass and to its weight?
- (A) Mass decreases, weight decreases
- (B) Mass stays the same, weight increases
- (C) Mass increases, weight stays the same
- (D) Mass stays the same, weight decreases
Show Answer
Answer: D – The object still contains the same amount of matter, so its mass is unchanged. Its weight falls because weight = mass × g and g is smaller on the Moon.
Q5. Which instrument measures weight directly?
- (A) A newtonmeter (spring balance)
- (B) A beam balance
- (C) A measuring cylinder
- (D) A stopwatch
Show Answer
Answer: A – A newtonmeter measures the pull of gravity on an object: a force, in newtons. A beam balance compares masses, and a measuring cylinder measures volume.
Q6. A beam balance is used to compare an unknown mass with standard masses. Why does it give the same result on the Moon as on the Earth?
- (A) Because g has the same value everywhere
- (B) Because gravity pulls equally on both sides of the balance, so the comparison of masses is unaffected
- (C) Because there is no gravity on the Moon
- (D) Because a balance measures weight in kilograms
Show Answer
Answer: B – The balance tips until the weights on both sides are equal. Since the same g acts on both pans, equal weights mean equal masses, whatever the value of g.
Q7. The inertia of an object is its resistance to a change in its velocity. The inertia of an object depends on its
- (A) weight only
- (B) speed only
- (C) mass
- (D) value of g in that place
Show Answer
Answer: C – The greater the mass, the greater the inertia: a larger force is needed to start it moving, stop it, or change its direction.
Q8. A loaded trolley and an empty trolley are pushed with the same force. The loaded trolley accelerates more slowly because
- (A) its weight is smaller
- (B) its larger mass gives it greater inertia
- (C) g is smaller for the loaded trolley
- (D) there is no friction acting on it
Show Answer
Answer: B – More mass means more inertia, so the same force produces a smaller acceleration.
Q9. The weight of an object near the Earth’s surface acts
- (A) equally in all directions
- (B) horizontally along the surface
- (C) away from the centre of the Earth
- (D) towards the centre of the Earth
Show Answer
Answer: D – Weight is the pull of gravity, so it acts towards the centre of the Earth – this is what we mean by “vertically downwards”.
Q10. Which statement about mass and weight is correct?
- (A) Mass and weight are two names for the same quantity
- (B) The weight of an object depends on the gravitational field strength where it is measured
- (C) Weight is measured in kilograms
- (D) The mass of an object is smaller on the Moon than on the Earth
Show Answer
Answer: B – Weight = mg, so if g changes (different planet, for example), the weight changes. Mass never changes with location, and weight is measured in newtons.
Weight Calculations W = mg
Q11. An object has a mass of 5.0 kg. Taking g = 10 N/kg, its weight is
- (A) 0.5 N
- (B) 5 N
- (C) 50 N
- (D) 500 N
Show Answer
Answer: C – W = mg = 5.0 × 10 = 50 N.
Q12. A student has a mass of 60 kg. Taking g = 9.8 N/kg, the student’s weight is
- (A) 5880 N
- (B) 588 N
- (C) 60 N
- (D) 6.1 N
Show Answer
Answer: B – W = mg = 60 × 9.8 = 588 N.
Q13. The weight of a bag is 450 N on Earth, where g = 10 N/kg. The mass of the bag is
- (A) 4.5 kg
- (B) 450 kg
- (C) 45 kg
- (D) 4500 kg
Show Answer
Answer: C – m = W / g = 450 / 10 = 45 kg.
Q14. On the Moon, g = 1.6 N/kg. The weight of a 10 kg rock on the Moon is
- (A) 1.6 N
- (B) 6.3 N
- (C) 100 N
- (D) 16 N
Show Answer
Answer: D – W = mg = 10 × 1.6 = 16 N. (On Earth the same rock would weigh about 98 N.)
Q15. An astronaut’s weight on Earth is 720 N, taking g = 10 N/kg. On the Moon (g = 1.6 N/kg), the astronaut’s weight is approximately
- (A) 115 N
- (B) 72 N
- (C) 450 N
- (D) 720 N
Show Answer
Answer: A – First find the mass: m = W / g = 720 / 10 = 72 kg. The mass is the same on the Moon, so W = mg = 72 × 1.6 = 115.2 N ≈ 115 N.
Q16. An object of mass 10 kg has a weight of 98 N. The value of g at this place is
- (A) 0.10 N/kg
- (B) 9.8 N/kg
- (C) 98 N/kg
- (D) 980 N/kg
Show Answer
Answer: B – g = W / m = 98 / 10 = 9.8 N/kg, the value at the Earth’s surface.
Q17. Taking g = 10 N/kg on Earth and g = 1.6 N/kg on the Moon, which object has the greatest weight?
- (A) A 1 kg mass on Earth
- (B) A 5 kg mass on the Moon
- (C) A 2 kg mass on Earth
- (D) A 4 kg mass on the Moon
Show Answer
Answer: C – Weights: (A) 1 × 10 = 10 N; (B) 5 × 1.6 = 8 N; (C) 2 × 10 = 20 N; (D) 4 × 1.6 = 6.4 N. The 2 kg mass on Earth is greatest.
Q18. A mass hangs from a spring balance inside a lift. The lift’s cable breaks and the lift falls freely (ignore air resistance). The reading on the spring balance is
- (A) the normal weight of the mass
- (B) zero
- (C) twice the normal weight
- (D) half the normal weight
Show Answer
Answer: B – In free fall, the mass and the balance fall together with acceleration g, so the spring is not stretched at all and reads zero. This is apparent weightlessness – gravity is still acting.
Q19. An object weighs 160 N on the Moon, where g = 1.6 N/kg. The mass of the object is
- (A) 1.6 kg
- (B) 16 kg
- (C) 256 kg
- (D) 100 kg
Show Answer
Answer: D – m = W / g = 160 / 1.6 = 100 kg. Its mass would still be 100 kg on Earth, where it would weigh about 980 N.
Q20. Object A has a mass of 3 kg and is on Earth (g = 10 N/kg). Object B has a mass of 8 kg and is on the Moon (g = 1.6 N/kg). Which statement is correct?
- (A) A weighs more than B
- (B) B weighs more than A
- (C) A and B have equal weights
- (D) Their weights cannot be compared because they are on different planets
Show Answer
Answer: A – Weight of A = 3 × 10 = 30 N. Weight of B = 8 × 1.6 = 12.8 N. So A weighs more, even though B has the larger mass.
Gravitational Field Strength & Centre of Mass
Q21. [Supplement] Gravitational field strength g is defined as
- (A) the mass of an object divided by its weight
- (B) the force of gravity acting per unit mass
- (C) the weight of an object multiplied by its mass
- (D) the total gravitational force on all objects in a field
Show Answer
Answer: B – g = W / m, the gravitational force experienced by each kilogram of mass placed in the field, measured in N/kg.
Q22. [Supplement] On a certain planet, g = 25 N/kg. This means that
- (A) each 1 kg mass experiences a gravitational force of 25 N
- (B) every object on the planet weighs 25 N
- (C) every object on the planet has a mass of 25 kg
- (D) g is measured in newtons
Show Answer
Answer: A – g is the weight per unit mass: every kilogram is pulled with a force of 25 N, so a 4 kg mass would weigh 4 × 25 = 100 N there.
Q23. [Supplement] Comparing the value of g at the Earth’s poles with its value at the equator, g is
- (A) slightly smaller at the poles
- (B) zero at the equator
- (C) exactly the same at both places
- (D) slightly greater at the poles
Show Answer
Answer: D – g is about 9.83 N/kg at the poles and about 9.78 N/kg at the equator. The difference is small, which is why we usually just use 9.8 or 10 N/kg.
Q24. [Supplement] A satellite moves to a higher orbit, further from the Earth’s surface. As its height above the surface increases, the value of g there
- (A) increases steadily
- (B) stays exactly the same
- (C) decreases
- (D) drops to zero as soon as it leaves the atmosphere
Show Answer
Answer: C – The Earth’s gravitational field gets weaker with distance, so g decreases with altitude – gradually, not suddenly at the edge of the atmosphere.
Q25. The centre of mass of an object is
- (A) the heaviest part of the object
- (B) a point on the surface of the object
- (C) the point at the centre of the object’s volume
- (D) the point through which the object’s weight may be considered to act
Show Answer
Answer: D – The centre of mass is the single point where all the mass (and so the weight) of the object can be treated as concentrated. It need not be at the centre of the volume, and it can even lie outside the material of the object.
Q26. A student hangs an irregular card from a pin through a hole near its edge, and hangs a plumb line from the same pin. She draws a line on the card along the plumb line. This line
- (A) passes through the centre of mass of the card
- (B) is an axis of symmetry of the card
- (C) shows where the card is heaviest
- (D) marks the exact centre of the card
Show Answer
Answer: A – When the card hangs freely, its centre of mass settles vertically below the pin, so it lies somewhere on the plumb line drawn on the card.
Q27. The centre of mass of a uniform metre rule is at the
- (A) 0 cm mark
- (B) 25 cm mark
- (C) 50 cm mark
- (D) 100 cm mark
Show Answer
Answer: C – The rule is uniform, so its mass is spread evenly and the centre of mass is at its midpoint, the 50 cm mark – the rule balances there.
Q28. An object standing on a table will topple over if
- (A) the vertical line through its centre of mass falls outside its base
- (B) its centre of mass is very low
- (C) it has a wide base
- (D) its mass is very small
Show Answer
Answer: A – Once the line of action of the weight falls outside the base, gravity pulls the object over. A low centre of mass and a wide base (options B and C) make this less likely, so they increase stability.
Q29. Racing cars are designed to be very stable at speed mainly because they have
- (A) a very large mass
- (B) a high centre of mass
- (C) a low centre of mass and a wide wheelbase
- (D) narrow tyres
Show Answer
Answer: C – A low centre of mass and a wide base mean the car must tilt a long way before the line through its centre of mass leaves the base, so it resists toppling on corners.
Q30. To locate the centre of mass of the card in Q26 exactly, the student repeats the plumb-line method from a second hole. The centre of mass is
- (A) somewhere on the first line only
- (B) at the second hole
- (C) at the point found by measuring the card’s length and width
- (D) at the intersection of the two drawn lines
Show Answer
Answer: D – Each plumb line passes through the centre of mass, so the centre of mass is where the two lines cross.
Keep Going
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All questions on this page are original practice questions written for QuaidianPoint. They are not Cambridge past-paper questions.