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Figure 9 shows a free body diagram for an aeroplane flying at a constant speed and at a constant height - AQA - GCSE Physics Combined Science - Question 6 - 2019 - Paper 2
Question 6
Figure 9 shows a free body diagram for an aeroplane flying at a constant speed and at a constant height. The speed of the aeroplane is much greater than the speed a... show full transcript
Worked Solution & Example Answer:Figure 9 shows a free body diagram for an aeroplane flying at a constant speed and at a constant height - AQA - GCSE Physics Combined Science - Question 6 - 2019 - Paper 2
Step 1
Explain how the forces need to change so the aeroplane can land.
Answer
To allow the aeroplane to land safely, the forces acting on it must adjust as follows:
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Decrease in Thrust: The thrust must decrease as the aeroplane prepares for landing. This allows for proper slowing down and helps control the descent.
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Increase in Air Resistance: As speed decreases, air resistance or drag increases, opposing the thrust and contributing to the reduction in speed.
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Reduction in Lift: The lift force must also decrease. As the weight of the aeroplane remains constant, and if lift is less than weight, the aeroplane will descend.
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Introduction of Downward Force: Consequently, with a decrease in lift and sustained weight, there emerges a resultant downward force which assists in the controlled landing.
Step 2
Calculate the mass of the aeroplane.
Answer
To calculate the mass of the aeroplane, we can use the equation of motion:
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Determine Deceleration:
Using the formula for acceleration, we have:
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Calculate Resultant Force:
We know that the mean resultant force ( F ) is given by:
Given that ( F = -750000 , N ) and ( a = -2.5 , m/s^2 $$, we can rearrange the formula to find mass ( m ):
( -750000 = m \cdot -2.5 )
- Solve for Mass:
( m = \frac{{-750000}}{{-2.5}} = 300000 , kg $$.
The mass of the aeroplane is therefore ( 300000 , kg ).