AQA GCSE Physics (8463), Higher tier · Forces › Forces and their interactions
Practise Gravity. 13 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Calculate the weight of the backpack on the Earth. gravitational field strength = 9.8 N/kg Use the equation: weight = mass × gravitational field strength
117.6 N (118 N) N
State the direction in which the weight of the boulder acts.
Towards the centre of the Earth (vertically downwards).
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy6 marks
An astronaut’s backpack has a mass of 12 kg.
(a) Calculate the weight of the backpack on the Earth. gravitational field strength = 9.8 N/kg Use the equation: weight = mass × gravitational field strength[2]
(b) The gravitational field strength on the Moon is 1.6 N/kg. Calculate the weight of the backpack on the Moon.[2]
(c) What is the mass of the backpack on the Moon?[1]
(d) Name the instrument used to measure weight.[1]
Show the answer and mark scheme
(a)Answer: 117.6 N (118 N) N
W = 12 × 9.8
117.6 (N)
(b)Answer: 19.2 N
W = 12 × 1.6
19.2 (N)
(c)Answer: 12 kg
12 (kg)
(d)Answer: A newtonmeter (calibrated spring balance).
newtonmeter / (calibrated) spring balance
Question 2Medium3 marks
(a) A student hangs a stone from a newtonmeter. In air, the newtonmeter reads 3.4 N. Calculate the mass of the stone. gravitational field strength = 9.8 N/kg[2]
(b) The student then lowers the stone, still hanging from the newtonmeter, until it is fully submerged in a beaker of water. The newtonmeter reading decreases. Suggest why.[1]
Show the answer and mark scheme
(a)Answer: 0.35 kg (0.347 kg) kg
m = 3.4 ÷ 9.8
0.35 (kg)
(b)Answer: The water exerts an upward force (upthrust) on the stone, so a smaller tension now supports it.
there is now an upward force (upthrust) from the water acting on the stone, in addition to its weight and the tension, so the tension needed to support it is less than its weight
Question 3Hard7 marks
An astronaut has a mass of 75 kg. The International Space Station (ISS) orbits about 400 km above the Earth’s surface. The gravitational field strength at the height of the ISS is 8.7 N/kg. Gravitational field strength at the Earth’s surface = 9.8 N/kg
(a) Calculate the weight of the astronaut on the surface of the Earth.[2]
(b) Calculate the percentage decrease in the weight of the astronaut when the astronaut is on the ISS, compared with on the surface of the Earth.[3]
(c) A student says: ‘Astronauts float inside the ISS because there is no gravity in space.’ Use the information to explain why the student is wrong.[2]
Show the answer and mark scheme
(a)Answer: 735 N
W = 75 × 9.8
735 (N)
(b)Answer: 11% (11.2%) %
weight on the ISS = 75 × 8.7 = 652.5 (N)
decrease = 735 − 652.5 = 82.5 (N)
(82.5 ÷ 735) × 100 = 11 (%)
(c)Answer: g at the ISS is 8.7 N/kg, so the astronaut still has a weight of about 650 N.
the gravitational field strength at the ISS is 8.7 N/kg, which is not zero
so the astronaut still has a (large) weight / a weight of about 650 N