A person saw a flash of lighting 15 seconds before he heard the first sound of thunder, Neglecting the effect of any wind, calculate the distance of the
lightning from the observer.Given that the velocities of sound and light ray
in the open air are 330m/s and 3 X 10^8m/s
Wave problem
2011-01-15 1:12 am
回答 (2)
2011-01-15 1:27 am
✔ 最佳答案
Suppose that the time for the flash to travel is negligible, i.e. the person can see the flash immediately as soon as it happens, thus:The sound needs 15 s to travel, i.e the distance of the lightning is 330 x 15 = 4950 m
參考: 原創答案
2011-01-15 6:10 am
let the distance be d.
then for the light, it has to travel d/3 X 10^8 seconds to reach the observer
for the sound, it has to travel d/330 seconds to reach the observer,
therefore d/330 - d/3 X 10^8 = 15
solving gives d = 4950m
then for the light, it has to travel d/3 X 10^8 seconds to reach the observer
for the sound, it has to travel d/330 seconds to reach the observer,
therefore d/330 - d/3 X 10^8 = 15
solving gives d = 4950m
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