AQA GCSE Physics (8463), Higher tier · Energy › Energy stores and changes
Practise Changes in energy. 14 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 kinetic energy of the runner. Use the equation: kinetic energy = 0.5 × mass × (speed)2
1470 J
Write down the equation that links kinetic energy (Ek), mass (m) and speed (v).
Ek = ½ m v2
Write down the equation that links gravitational field strength (g), gravitational potential energy (Ep), height (h) and mass (m).
Ep = m g h
State the two factors that determine the kinetic energy of a moving object.
Mass and speed.
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
A runner of mass 60 kg is running at a speed of 7.0 m/s.
(a) Calculate the kinetic energy of the runner. Use the equation: kinetic energy = 0.5 × mass × (speed)2[2]
(b) After the run, the runner lifts a box of mass 12 kg onto a shelf 1.5 m above the floor. Gravitational field strength = 9.8 N/kg Calculate the increase in the gravitational potential energy of the box. Use the equation: gravitational potential energy = mass × gravitational field strength × height[2]
(c) What is the unit of energy? Tick (✓) one box.[1]
joule
kilogram
newton
watt
Show the answer and mark scheme
(a)Answer: 1470 J
Ek = 0.5 × 60 × 7.02
Ek = 1470 (J)
(b)Answer: 176.4 J
Ep = 12 × 9.8 × 1.5
Ep = 176.4 (J)
(c)Answer: joule
Question 2Medium7 marks
A drone is used to take photographs. The drone has a mass of 1.2 kg.
(a) Write down the equation that links kinetic energy (Ek), mass (m) and speed (v).[1]
(b) When the drone is flying horizontally it has 60 J of kinetic energy. Calculate the speed of the drone.[3]
(c) The drone then rises vertically through 25 m at a constant speed. Gravitational field strength = 9.8 N/kg Calculate the increase in the gravitational potential energy of the drone.[2]
(d) Explain why the kinetic energy of the drone does not change as it rises.[1]
Show the answer and mark scheme
(a)Answer: Ek = ½ m v2
Ek = ½ × m × v2 / kinetic energy = 0.5 × mass × (speed)2
(b)Answer: 10 m/s
60 = 0.5 × 1.2 × v2
v2 = 100
v = 10 (m/s)
(c)Answer: 294 J
Ep = 1.2 × 9.8 × 25
Ep = 294 (J)
(d)Answer: Its speed (and mass) stay the same.
the speed (and mass) of the drone is constant
Question 3Hard9 marks
A toy launcher uses a compressed spring to fire a small ball horizontally. The spring constant of the spring is 250 N/m. The spring is compressed by 8.0 cm before the ball is released. The mass of the ball is 20 g.
(a) Calculate the elastic potential energy stored in the spring. Use the Physics Equations Sheet.[3]
(b) Calculate the maximum possible speed of the ball as it leaves the launcher. Give your answer to 2 significant figures.[3]
(c) The actual speed of the ball as it leaves the launcher is 7.5 m/s. Calculate the percentage of the elastic potential energy that is transferred to the kinetic energy store of the ball.[3]