- #1
JimT
Dear all,
I have been working my way through the Oxford University physics test sample paper http://www.physics.ox.ac.uk/admissions/combined-sample.pdf" and I have come across this question:
A sky-diver jumps out of an aeroplane. Which of the following statements is true after she reaches terminal velocity?
A The force of air resistance is the same size as her weight.
B The force of air resistance is larger than her weight.
C The force of air resistance is smaller than her weight.
D She begins to slow down.
Now my initial answer would be A however, after thinking about it would I be correct in believing that the answer would be in fact D as air density decreases with increase in altitude? The net force, if the sky-diver stayed at a constant terminal velocity, would steadily become greater in magnitude (after reaching initial terminal velocity) in the upwards direction as a result of increased air resistance due to an increase in air density. To resolve this net difference, the sky-diver's velocity would decrease thus lowering drag until the net force=0?
Would that be correct? As far as I can see, both A and D are true.
Best wishes,
James
I have been working my way through the Oxford University physics test sample paper http://www.physics.ox.ac.uk/admissions/combined-sample.pdf" and I have come across this question:
A sky-diver jumps out of an aeroplane. Which of the following statements is true after she reaches terminal velocity?
A The force of air resistance is the same size as her weight.
B The force of air resistance is larger than her weight.
C The force of air resistance is smaller than her weight.
D She begins to slow down.
Now my initial answer would be A however, after thinking about it would I be correct in believing that the answer would be in fact D as air density decreases with increase in altitude? The net force, if the sky-diver stayed at a constant terminal velocity, would steadily become greater in magnitude (after reaching initial terminal velocity) in the upwards direction as a result of increased air resistance due to an increase in air density. To resolve this net difference, the sky-diver's velocity would decrease thus lowering drag until the net force=0?
Would that be correct? As far as I can see, both A and D are true.
Best wishes,
James
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