Physics 0625 · syllabus 1.3
Cambridge IGCSE Physics 0625 — Mass and weight topical past papers
Why mass and weight are different quantities, gravitational field strength and g = W/m, weight on other planets, and comparing masses and weights with a balance.
- Questions
- 1,118
- Years
- 2009–2026
- With mark scheme
- 100%
- Questions 2022–2026
- 425
Anyone can browse these pages. Opening the questions and their mark schemes takes a free Momentum account.
What Mass and weight covers
Everyday speech treats mass and weight as the same thing, but physics keeps them apart. Mass tells you how much matter an object contains, is measured in kilograms and stays the same wherever the object is taken. Weight is the pull of gravity on that matter, a force measured in newtons, and it depends on the gravitational field the object is in.
Gravitational field strength g is the gravitational force on each kilogram, so g = W/m, and at the Earth's surface it is about 9.8 N/kg. It has the same value as the acceleration of free fall, 9.8 m/s², because an object acted on by its weight alone accelerates at g. On the Moon, where g is about 1.6 N/kg, a 60 kg astronaut still has a mass of 60 kg but weighs about 96 N instead of about 590 N.
A balance compares weights, and because both objects sit in the same field it compares their masses too. Extended candidates treat weight as what a gravitational field does to any mass placed in it, an idea that returns in space physics, where the field is different on each planet and weakens with distance. The topic is short, but turning a mass into a weight is the first step in questions on moments, pressure, work and gravitational potential energy, so it is tested well beyond its own questions.
In the syllabus
The headings this topic has in the Cambridge International 2026–2028 syllabus, as the board prints them.
- 1.3 Mass and weight
What you should be able to do
- State what mass and weight each measure, and the unit of each
- Use g = W/m to find a weight, a mass or a gravitational field strength
- Explain why an object's weight changes from one planet to another while its mass stays the same
- Explain why a balance that compares weights also compares masses
- Explain weight as the result of a gravitational field acting on a mass (Extended)
Key ideas
- Mass (kg): how much matter an object contains; it is the same everywhere
- Weight (N): the gravitational force on an object, acting towards the centre of the planet
- Gravitational field strength g = W/m, in N/kg; about 9.8 N/kg at the Earth's surface
- g in N/kg has the same value as the acceleration of free fall in m/s²
How Mass and weight has been examined
From 2022 to 2026, Mass and weight was on Paper 4 · Theory (Extended) in 14 of 14 exam series, worth about 18% of that paper’s marks.
| Paper | Questions | Share of marks | Series |
|---|---|---|---|
| Paper 1 · Multiple Choice (Core) | 124 | 10% | 14 of 14 |
| Paper 2 · Multiple Choice (Extended) | 172 | 13% | 14 of 14 |
| Paper 3 · Theory (Core) | 48 | 15% | 14 of 14 |
| Paper 4 · Theory (Extended) | 58 | 18% | 14 of 14 |
| Paper 6 · Alternative to Practical | 23 | 17% | 12 of 14 |
Momentum’s own count, over the questions in its bank for these years: a series is one exam session, every zone included, and a question filed under two chapters counts in both. Median marks per question: 1. The bank files this topic together with neighbouring ones, so these figures count every question in its chapters, including some on those topics.
Filed in Momentum under: Forces and Motion.
A worked example
A rover has a mass of 180 kg. On the surface of Mars it weighs 670 N. Find the gravitational field strength on Mars, and the rover's weight on Earth, where g = 9.8 N/kg.
- On Mars: g = W/m = 670 / 180 = 3.7 N/kg
- The rover's mass is 180 kg wherever it is
- On Earth: W = mg = 180 × 9.8 = 1764 N
- Check: the field on Mars is weaker, so the rover weighs less there, 670 N against about 1760 N
Answer: About 3.7 N/kg on Mars; about 1.8 × 10³ N on Earth
Written by Momentum for this page, with its own numbers; it is not taken from a past paper.
Mistakes that cost marks
- Giving a weight in kilograms — weight is a force, so it is in newtons: a 5.0 kg bag weighs 49 N on Earth
- Forgetting to change grams into kilograms — a 250 g apple weighs 0.25 × 9.8 = 2.5 N, not 2450 N
- Saying an astronaut's mass falls on the Moon — the amount of matter is unchanged; only the gravitational force on it is smaller
- Saying a balance can only compare weights — two objects that balance in the same field have equal weights, so they also have equal masses
Exam technique
- Write g = W/m, rearrange it before substituting, and give the unit — N, kg or N/kg — with the answer
- When asked for the difference between mass and weight, define each, give each unit, and say which one changes from place to place
- Use the value of g the question gives, and carry the weight you calculate into later parts of the same question
Practising in Momentum
- Every question in a chapter as one list, from every paper and year in the bank, newest first or shuffled.
- Each question turns over to its own part of the mark scheme, where the board published one.
- Narrow by paper, year, session, zone and marks, and star the questions worth keeping.
- Pick chapters, a number of questions and a time, and the exam builder draws a mock to sit and mark.
Past-paper questions and mark schemes are the copyright of Cambridge International. Momentum shows them to signed-in learners for revision and does not publish them on these pages.