Check out some similar questions!

Rubentheran · Jan 12, 2011, 04:56 AM

A helicopter drops a paratrooper carrying a buzzer that emits a 500 Hz signal. A sound receiver on the plane monitors the signal as the paratrooper falls. If the perceived frequency becomes constant at 450 Hz, what is the terminal speed at the paratrooper ? Take the speed sound in air to be 343 m/s and assume the paratrooper always remains below the helicopter.

ebaines · Jan 12, 2011, 06:31 AM

The percentage change in frequency heard by the helicopter is equal to the ratio of the paratrooper's speed to the speed of sound. Can you complete this now?

Rubentheran · Jan 12, 2011, 06:40 AM

How to do it?

ebaines · Jan 12, 2011, 07:08 AM

Let:

$ v_s = speed\ of\ sound\\ v_p\ =\ speed\ of\ paratrooper\\ f_e\ =\ frequency\ of\ signal\ emitted\ by\ the\ beeper\\ f_r\ =\ frequency\ of\ signal\ received\ at\ the\ helicopter $

Then:

$ \Delta f = f_e-f_r \\ \frac {\Delta f} {f_e} = \frac {v_p} {v_s} $

You have all the data you need to rearrange and solve for $v_p$ .

Rubentheran · Jan 12, 2011, 07:26 AM

Thanks