Wave Velocity Analysis #1
Name
Date
Per
1. Write out the equations related to waves and sound. (Try to connect wavelength, frequency, period and
velocity.)
2. Quick velocity wave problems. Note: the speed (velocity) of sound is approximately 343 m/s in air.
i. WRITE the equation first
ii. put in your numbers with units
iii. solve it and box your final answer
a. You put your hand under your armpit and quickly lower your arm, making a funny noise. How long does
it take for this sound to reach your sister, who is sitting across the room, 21 m away?
(ans: 0.0612 s)
b. You are at a track meet sitting in the stadium. The race starter is 180 m away. You see the flash and the
smoke as she fires the start pistol. How long do you have to wait to hear the bang of the gun? (ans: 0.525 s)
c. At a 4th of July show, you see a firework start to spread out in the sky overhead. Moments later, you
hear the boom. If you time it and find that the boom is heard 0.311 s after it exploded and started to spread,
how high was the firework when it exploded?
(ans: 107 m)
d. During a storm, you see a flash from lightning. Then, 2.5 seconds later, you hear the crash of the
thunder. How far away was the lightning? (Thunder is created whenever lightning strikes.)
(ans: 860 m)
e. Since there are 1609 m = 1 mi, use your answer from d to estimate how long you have to wait between
the flash of lightning and the crash of thunder, if the lightning is about one mile away.