This preview shows page 1. Sign up to view the full content.
Unformatted text preview: ething is when it happened (at least for events
here on Earth). You can determine how far away a lightning strike is by
counting seconds from the time you see the lightning until you hear the
thunder. It takes sound about 5 s to travel a mile, so if the thunder lags
behind the lightning by 2 or 3 s, then the lightning strike occurred about half
a mile away.
Problem: You hear a thunder clap 6 s after
you see the lightning. Assume the speed of
sound to be 343 m/s. How far away is the
(Solution on next slide) Light Vs. Sound (cont.)
Answer: Ignoring the small amount of time light needs to travel to you,
d = v t = (343 m/s) (6 s) = 2058 m
Problem: Now let’s do the same problem without ignoring light’s travel
time: Light Waves Sound Waves
Solution on next slide Light Vs. Sound (cont.) Answer: Let t = time it takes the light to reach you. In that
time the sound of the thunder only travels a short distance.
Since you hear the thunder 6 s after you see the lightning,
the sound travels for (6 s) + t. The light and sound each
travel the same distance, so:
View Full Document
This note was uploaded on 11/17/2011 for the course PHYS 121 taught by Professor Burgeson during the Fall '11 term at BYU.
- Fall '11