Question

According to a rule-of-thumb, each five seconds between a lightning flash and the following thunder gives the distance to the flash in miles. (a) Assuming that the flash of light arrives in essentially no time at all, estimate the speed of sound in m/s from this rule. (b) What was your average speed?

Answer 1

There are approximately 1600 meters/mile. Estimating a five second per mile delay in the arrival of the sound, then the estimate of the speed of sound is (a)1600/5 or 320 meters/sec or (B) 320 x 60 sec x 60 min / 1600 m/mile or about 720 miles/hour.