Q. While on holiday a group of friends decide to take part in a skydive. After a period of
free
fall the first friend releases her parachute to reduce the speed she falls to Earth at.
a) Explain how a scientific understanding of drag would benefit sports such as
skydiving.
(2)
The skydiving company has only catered for skydivers ranging from 50–90 kg. Two of
the
friends are over 90 kg.
b)
c)
Explain what effect this will to have on their motion during their skydive.
(2)
Suggest how the company could compensate for the additional mass of the
skydivers.
(1)
d) Explain how a skydiver reaches terminal velocity.
(3)
e) Sketch a velocity–time graph and acceleration–time graph to illustrate a skydiver’s
motion before the parachute is opened.
(2)
f) Explain how the acceleration–time graph would alter if the effect of air resistance
wasn’t present.
b)
c)
d)
e)
An understanding of drag, the factors that affect it and how to control it allows for effective
safety measures and procedures to be implemented to ensure the safety of the skydivers. (2)

If the mass of the skydiver increases, the weight will increase. (1)
 Therefore, the skydiver will experience a greater net force in the downwards direction
and therefore will fall to the ground with an increased velocity. (1)
To ensure that the skydiver can reach terminal velocity (or a constant velocity) within
enough time so the diver is not still accelerating when he reaches the ground, the company
could introduce any one of the following:

A parachute with increased cross-sectional area to increase the drag force acting
upwards (1)
 Alter the timings of the parachute release, in order to increase the time period the
skydiver has in which to decelerate and reach terminal velocity (1)
Give full marks for any suitable answer.
 As the skydiver initially jumps out of the plane, only weight is acting on the skydiver
and the acceleration rate is 9.81 ms −2 . (1)
 As the skydiver’s speed increases, the contribution of drag also increases, reducing the
net force and the rate at which the skydiver accelerates to the ground. (1)
 Eventually the drag force will be equal to the weight of the skydiver, and therefore the
net force and acceleration will be zero and the skydiver will reach a constant terminal
velocity. (1)
1 mark for each correct graph.
Acceleration/ms −2
a)
Velocity/ms −1
A.
Time/s
f)
Time/s
If air resistance was not present there would be no drag force and therefore the skydiver
would accelerate at a constant rate of 9.81 ms −2 . (1)
(1)