Who this is for: Cambridge IGCSE Coordinated Science (0654) students who want mass and weight — definitions, units and W = mg — to become a reliable source of marks instead of a swapped-vocabulary trap.
What query it owns: how to understand and revise mass and weight in Cambridge IGCSE Coordinated Science.
Why this is safe: this page owns the mass-and-weight revision-guide angle, while Tutopiya’s Mass And Weight subtopic page owns the learning resource and the free Mass And Weight quiz owns the practice.

Mass and weight are not the same quantity. Cambridge IGCSE Coordinated Science (0654) expects you to define each, use correct units, apply W = mg, and choose the right measuring instrument. This guide separates the two concepts so you never swap them in an exam answer.

Key takeaways

• Mass is the amount of matter in an object; unit kilogram (kg); measured with a balance.
• Weight is the gravitational force on an object; unit newton (N); measured with a spring balance (force meter).
• Weight = mass × gravitational field strength → W = mg.
• On Earth, g ≈ 10 N/kg (or 10 m/s²).
• Mass is constant everywhere; weight varies with gravitational field strength.

What are mass and weight in Cambridge IGCSE Coordinated Science?

Mass measures how much matter an object contains — it does not change if you move to the Moon. Weight is the force with which gravity pulls on that mass. Because weight is a force, it is measured in newtons. The link between them is W = mg, where g is the gravitational field strength.

You can read the full explanation, diagrams and notes on Tutopiya’s Mass And Weight subtopic page before you attempt questions.

Mass vs weight — comparison table

Property	Mass	Weight
Definition	Amount of matter	Gravitational force on an object
Unit	kilogram (kg)	newton (N)
Instrument	Balance (compares mass)	Spring balance / force meter
Changes with location?	No	Yes (depends on g)
Type of quantity	Scalar	Force (vector)

The equation W = mg

Symbol	Meaning	Typical value
W	Weight	in N
m	Mass	in kg
g	Gravitational field strength	~10 N/kg on Earth

Example: a 5 kg object on Earth has weight W = 5 × 10 = 50 N.

Mass and weight in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical mass/weight stem
Define	Give precise meaning	”Define mass.” / “Define weight.”
Calculate	Use W = mg	”Calculate the weight of a 3 kg object.”
State the unit	Give correct SI unit	”State the SI unit of weight.”
Explain	Link concept to observation	”Explain why an astronaut’s weight changes on the Moon but mass does not.”

Worked exam-style stems (how to answer the wording)

1. “Define mass.” The amount of matter in an object. Mark-scheme reward: amount of matter (not weight).
2. “Calculate the weight of a 4 kg object on Earth (g = 10 N/kg).” W = mg = 4 × 10 = 40 N. Reward: correct substitution, unit N.
3. “State the instrument used to measure mass.” A balance. Reward: balance (not spring balance).

Test yourself with the Mass And Weight quiz once you can define both terms and use W = mg confidently.

How mass and weight connect to the rest of Coordinated Science physics

Mass and weight link to Density (ρ = m/V) and Forces — weight is a gravitational force. They also underpin Energy calculations involving gravitational potential energy. The Cambridge IGCSE Coordinated Science resource hub links every Motion subtopic.

Common mistakes students make

• Stating mass is measured in newtons (mass is in kg).
• Using a spring balance to measure mass (it measures weight/force).
• Saying mass changes on the Moon (mass is constant; weight changes).
• Forgetting the unit of g is N/kg (or m/s²), not N.
• Defining weight as “how heavy something is” without calling it a force.

When you need more support

If mass-and-weight questions keep costing marks, work through the Mass And Weight quiz, then get focused help from a Cambridge IGCSE Coordinated Science tutor.

Frequently asked questions

Is mass and weight hard in Coordinated Science? The distinction is simple once you remember mass is kg on a balance and weight is N from W = mg.

What is the difference between mass and weight? Mass is the amount of matter (kg); weight is the gravitational force on that mass (N).

What instrument measures weight? A spring balance or force meter — it measures force in newtons.

How do I revise mass and weight effectively? Learn definitions, units and W = mg, then take the Mass And Weight quiz.

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