Fig. 1 shows a velocity-time graph for a parachutist from the moment she leaves a balloon. Air resistance changes as her speed increases. The parachutist ha...
Question 1 Report
Fig. 1 shows a velocity-time graph for a parachutist from the moment she leaves a balloon. Air resistance changes as her speed increases. The parachutist has a mass of 68 kg and reaches a constant speed before opening her parachute.
(a) State what happens to the velocity after point A. [1]
(b) Explain why the parachutist has zero acceleration after point A. [2]
(c) State the name given to this constant velocity. [1]
Answer Details
(a) After A, the velocity-time graph is horizontal. The parachutist’s velocity remains constant. [1]
(b) As speed increases, air resistance increases. At A and afterwards, air resistance equals the parachutist’s weight, so the forces are balanced. The resultant force is therefore zero; by Newton’s second law, the acceleration is zero. [2]
(c) This constant falling velocity is called terminal velocity. [1]
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