The sound of thunder travels at a speed of 340 m/s and reaches you 2.5 s after you see a lightning flash. How far away is the lightning?

1 Answer
Dwight
Feb 4, 2018

The lightning was 850 m away.

Explanation:

This is like any other problem that deals with motion at constant speed. To find distance travelled, you multiply speed by time taken:

#d=vxxt = 340 m/s xx 2.5 s = 850m#

The sound has travelled at steady speed from the same source as the lightning, but the speed of the light was so great (#3xx10^8 m/s#) that we ignore the time it took to reach you.

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