IB DP Physics-Topic 1. Measurements and uncertainties-1.3 Vectors and scalars HL Paper 1

Question

A sky diver is falling at terminal speed when she opens her parachute.

What are the direction of her velocity vector and the direction of her acceleration vector before she reaches the new terminal speed?

 

Direction of velocity vector

Direction of acceleration vector

A.

upwards

upwards

B.

upwards

downwards

C.

downwards

upwards

D.

downwards

downwards

Answer/Explanation

Ans: C

When the parachutist is falling at terminal velocity, the upwards air resistance is equal to the weight of the parachutist. The resultant force is zero and the velocity is downwards.

When the parachute opens, the air resistance increases and is now greater than the weight.

The resultant force is now upwards and the acceleration is upwards. The velocity is still downwards.