The Physics Question Bank

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

The equation

gravitational potential energy = mass × gravitational field strength × height    Eₚ = m g h

Quantity	Symbol	Unit
gravitational potential energy	Eₚ	joules (J)
mass	m	kilograms (kg)
gravitational field strength	g	newtons per kilogram (N/kg)
height	h	metres (m)

Rearranged: h = Eₚ ÷ (m g)  |  m = Eₚ ÷ (g h)  |  g = Eₚ ÷ (m h)  |  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.

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Questions

Q1 (F) A 2.0 kg school bag is lifted 1.5 m onto a table. Calculate the gain in gravitational potential energy. (g = 9.8 N/kg)

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F: Eₚ = m g h
I: Eₚ = 2.0 × 9.8 × 1.5
F: Eₚ is already the subject
A: 29.4 J

Q2 (F) A 50 kg climber gains 9800 J of gravitational potential energy on a climbing wall. How high does she climb? (g = 9.8 N/kg)

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F: Eₚ = m g h
I: 9800 = 50 × 9.8 × h, so 9800 = 490 × h
F: h = 9800 ÷ 490
A: 20 m

Q3 (F) A forklift lifts a crate 4.0 m, giving it 1960 J of gravitational potential energy. Calculate the mass of the crate. (g = 9.8 N/kg)

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F: Eₚ = m g h
I: 1960 = m × 9.8 × 4.0, so 1960 = 39.2 × m
F: m = 1960 ÷ 39.2
A: 50 kg

Q4 (F) A 250 g apple falls from a tree and loses 4.9 J of gravitational potential energy. How far does it fall? (g = 9.8 N/kg)

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Convert first: 250 g = 0.25 kg
F: Eₚ = m g h
I: 4.9 = 0.25 × 9.8 × h, so 4.9 = 2.45 × h
F: h = 4.9 ÷ 2.45
A: 2 m

Q5 (F) A 60 kg hiker gains 294 kJ of gravitational potential energy climbing a hill. How high is the hill? (g = 9.8 N/kg)

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Convert first: 294 kJ = 294 000 J
F: Eₚ = m g h
I: 294 000 = 60 × 9.8 × h, so 294 000 = 588 × h
F: h = 294 000 ÷ 588
A: 500 m

Q6 (F/H) On the Moon, an astronaut lifts a 20 kg rock 1.5 m. It gains 48 J of gravitational potential energy. Calculate g on the Moon.

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F: Eₚ = m g h
I: 48 = 20 × g × 1.5, so 48 = 30 × g
F: g = 48 ÷ 30
A: 1.6 N/kg

Q7 (F/H) A lift and its passengers have a total mass of 1200 kg. The lift gains 352.8 kJ of gravitational potential energy. How high does it rise? (g = 9.8 N/kg)

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Convert first: 352.8 kJ = 352 800 J
F: Eₚ = m g h
I: 352 800 = 1200 × 9.8 × h, so 352 800 = 11 760 × h
F: h = 352 800 ÷ 11 760
A: 30 m

Q8 (F/H) The water in a hydroelectric reservoir stores 2.94 × 10¹² J of gravitational potential energy, 150 m above the turbines. Calculate the mass of water. (g = 9.8 N/kg)

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F: Eₚ = m g h
I: 2.94 × 10¹² = m × 9.8 × 150, so 2.94 × 10¹² = 1470 × m
F: m = 2.94 × 10¹² ÷ 1470
A: 2.0 × 10⁹ kg

Q9 (H) A 60 kg diver steps off a 10 m diving board. Calculate her speed as she enters the water. (g = 9.8 N/kg; ignore air resistance)

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Step 1 – GPE lost: Eₚ = m g h = 60 × 9.8 × 10 = 5880 J = Eₖ gained
Step 2 – speed
F: Eₖ = ½ m v²
I: 5880 = 0.5 × 60 × v², so 5880 = 30 × v²
F: v² = 196, so v = √196
A: 14 m/s

Q10 (H) A pumped-storage power station transfers 1.8 × 10⁸ J to lift water 320 m uphill. Calculate the mass of water lifted, in standard form to 2 significant figures. (g = 9.8 N/kg)

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F: Eₚ = m g h
I: 1.8 × 10⁸ = m × 9.8 × 320, so 1.8 × 10⁸ = 3136 × m
F: m = 1.8 × 10⁸ ÷ 3136 = 57 397… kg
A: 5.7 × 10⁴ kg (2 s.f.)