Question

In a scene from the movie 'Matrix Reloaded', Trinity (one of the 'good characters') is falling out a high window towards the ground with agent Johnson (a 'bad guy') falling out of the window towards her. (The agent falls from the window after Trinity does, so the agent is above (further from the ground) than Trinity.) While falling, Trinity fires her gun upwards at the agent. Let's make the following assumptions: Trinity's speed towards the ground is 54 m/s (she has reached terminal velocity, so her velocity is constant). The sound from her gun has a frequency of 710 Hz. The gunshot (sound from gun) echoes off of the agent, and the frequency of the echo that Trinity hears is 714 Hz. Furthermore, assume the agent is also falling at a constant (terminal) speed, but for various reasons, the agent's speed is different than Trinity's speed. Based on the above assumptions, what is the speed of the agent?

Answer 1

this is the problem of doppler effect

relavent formula for this

fs=(C/C-Vs)*f0

f_O is the observed frequency

f_S is the emitted frequency

c is the velocity of sound =340 m/s

714 = (340/(340-V)*710

V= 1.905 m/s

thus speed of agent = V+54 =55.905 m/s

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