The Physics Question Bank

Ramped Questions for GCSE Physics

Weight = Mass × Gravitational Field Strength (W = mg)

✏️ Paper first! Work out every question on paper before you tap Show solution. Write down every step – the equation, the numbers with units, the rearranging and the answer with its unit. In the exam, if your final answer is wrong you can still get marks for correct working, but only if the examiner can see it.

Course: Combined Science + Separate Physics  |  Tier: Foundation + Higher  |  Equation sheet: given in the exam

The equation

weight = mass × gravitational field strength    W = m g

QuantitySymbolUnit
weightWnewtons (N)
massmkilograms (kg)
gravitational field strengthgnewtons per kilogram (N/kg)

Rearranged: m = W ÷ g   |   g = W ÷ m   |   On Earth, g = 9.8 N/kg

Use FIFA for every answer

  • F – Formula: write the equation as it appears on the sheet.
  • I – Insert: put in the numbers (convert to standard units first).
  • F – Fix: rearrange to make the unknown the subject.
  • A – Answer: calculate and always give the unit.

Foundation: aim for Q1–8.   Higher: aim for Q4–10. Most questions need rearranging.

Questions

Q1 (F) A bag of shopping has a mass of 5 kg. Calculate its weight on Earth. (g = 9.8 N/kg)

Show solution

F: W = m g
I: W = 5 × 9.8
F: W is already the subject – no rearranging needed
A: 49 N

Q2 (F) At airport check-in, a suitcase has a weight of 196 N. Calculate its mass. (g = 9.8 N/kg)

Show solution

F: W = m g
I: 196 = m × 9.8
F: m = 196 ÷ 9.8
A: 20 kg

Q3 (F) An astronaut with a mass of 80 kg has a weight of 128 N on the Moon. Calculate the gravitational field strength on the Moon.

Show solution

F: W = m g
I: 128 = 80 × g
F: g = 128 ÷ 80
A: 1.6 N/kg

Q4 (F) A bag of flour has a weight of 14.7 N. Calculate its mass in grams. (g = 9.8 N/kg)

Show solution

F: W = m g
I: 14.7 = m × 9.8
F: m = 14.7 ÷ 9.8 = 1.5 kg
A: 1.5 × 1000 = 1500 g

Q5 (F) A loaded delivery van has a weight of 24.5 kN. Calculate its mass. (g = 9.8 N/kg)

Show solution

Convert first: 24.5 kN = 24 500 N
F: W = m g
I: 24 500 = m × 9.8
F: m = 24 500 ÷ 9.8
A: 2500 kg

Q6 (F/H) A Mars rover has a mass of 1000 kg. On Mars it has a weight of 3.7 kN. Calculate the gravitational field strength on Mars.

Show solution

Convert first: 3.7 kN = 3700 N
F: W = m g
I: 3700 = 1000 × g
F: g = 3700 ÷ 1000
A: 3.7 N/kg

Q7 (F/H) A crane cable can safely hold a maximum weight of 29.4 kN. Each concrete block has a mass of 150 kg. What is the greatest number of blocks the crane can lift at once? (g = 9.8 N/kg)

Show solution

Convert first: 29.4 kN = 29 400 N
F: W = m g
I: 29 400 = m × 9.8
F: m = 29 400 ÷ 9.8 = 3000 kg
A: 3000 ÷ 150 = 20 blocks

Q8 (F/H) A large cargo ship has a weight of 1.96 × 109 N. Calculate its mass. Give your answer in standard form. (g = 9.8 N/kg)

Show solution

F: W = m g
I: 1.96 × 109 = m × 9.8
F: m = 1.96 × 109 ÷ 9.8
A: 2.0 × 108 kg

Q9 (H) A rover has a weight of 3700 N on Mars, where g = 3.7 N/kg. Calculate its weight on Earth, where g = 9.8 N/kg.

Show solution

Step 1 – find the mass (it is the same everywhere)
F: W = m g
I: 3700 = m × 3.7
F: m = 3700 ÷ 3.7 = 1000 kg
Step 2 – weight on Earth
F: W = m g
I: W = 1000 × 9.8
A: 9800 N
Watch out: mass does not change between planets; weight does.

Q10 (H) The International Space Station has a mass of 420 000 kg. At its orbit height, its weight is 3.65 × 106 N. Calculate the gravitational field strength at that height. Give your answer to 2 significant figures.

Show solution

F: W = m g
I: 3.65 × 106 = 420 000 × g
F: g = 3.65 × 106 ÷ 420 000
A: 8.69… = 8.7 N/kg (2 s.f.)
Astronauts float because they are in free fall, not because there is no gravity.