Figure 4 shows a drone - Edexcel - GCSE Physics Combined Science - Question 2 - 2020 - Paper 1
Question 2
Figure 4 shows a drone.
The drone has four spinning blades.
The upward force produced enables the drone to rise in the air.
The speed at which the blades spin is ... show full transcript
Worked Solution & Example Answer:Figure 4 shows a drone - Edexcel - GCSE Physics Combined Science - Question 2 - 2020 - Paper 1
Step 1
Describe the relationship between upward force and speed shown by this graph.
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Answer
The relationship shown in the graph is that the upward force produced by the drone's blades increases with the speed at which they spin. This indicates a non-linear relationship, where the upward force rises exponentially as the speed increases, particularly noticeable beyond a threshold of around 1000 turns per minute, where no upward force is generated initially.
Step 2
(i) Calculate the change in gravitational potential energy when the drone rises through a height of 20 m.
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Answer
The gravitational potential energy (gpe) can be calculated using the formula:
extgpe=mimesgimesh
Substituting the values:
Mass (m) = 4.5 kg
Gravitational field strength (g) = 10 N/kg
Height (h) = 20 m
Thus,
extgpe=4.5imes10imes20=900extJ
Step 3
(ii) State the amount of useful work done by the blades as the drone rises through 20 m.
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Answer
The useful work done by the blades as the drone rises through 20 m is equal to the change in gravitational potential energy, which is 900 J.
Step 4
(iii) Calculate the useful power developed by the blades in this time of 4 s.
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Answer
Power can be calculated using the formula:
extpower=time takenwork done
The work done is 900 J and the time taken is 4 seconds:
power=4900=225extW
Thus, the useful power developed by the blades is 225 W.
