Question

A jet airplane is traveling west from Austin, Texas to Miami, Florida. It has an average speed with no wind of 600 mph. An observer on the ground records the airplane of having a speed of 580 mph. What speed and direction is the wind moving?

Answer 1

Answer: 20 mph due East from Austin

Explanation:

The relative speed of A with respect to B is given by:

$v_{AB}=v_A-v_B$

It is given that average speed of jet airplane travelling west from Texas to Miami is 600 mph.

$v_A=600 mph$

The speed of the airplane as measured by the observer on the ground:

$v_{AB} = 580 mph$

This is the relative speed  of the airplane with respect to wind measured by the observer on the ground.

We need to find the speed of the wind:

$v_B=v_A-v_{AB}$

$\Rightarrow v_B=600mph-580 mph=20mph$

As the relative speed is slower, it means the wind is blowing in the opposite direction.

Thus, the speed and direction of blowing wind is 20 mph due East from Austin