Question

Question 9 (1 point) [IDFDVFCMJI] While leaving the movie theatre after a great show, Matt Damon comments on how cold it is outside and asks you if you have any idea how cold it actually is. You know that you are standing 68.0 m away from the high exterior walls of the theatre. Matt Damon claps his hands loudly and you hear the echo of your clap 0.47 s later; you were timing this with an extremely accurate stopwatch. Calculate the temperature and impress Matt Damon.

Answer 1

Step 1: Find speed of sound

We know that wall is at 68.0 m from you and you hear the echo of clap after 0.47 sec, So

Speed of sound = distance traveled/time taken

distance traveled = 2*68.0 = 136.0 m, since sound clap sound goes to wall, and then echo returns.

t = total time taken = 0.47 sec

So,

Speed of sound = 136.0 m/0.47 sec = 289.4 m/s

Step 2: Now relation between speed of sound and temperature is given by:

V = 331 + 0.6*T

Where V = speed of sound at T temperature = 289.4 m/s

So,

T = (V - 331)/0.6

T = (289.4 - 331)/0.6

T = -69.33 C = Temperature outside movie theatre