## College Physics (4th Edition)

(a) $v = 338.2~m/s$ (b) The lightning strike is $2.8~km$ away.
(a) We can find the speed of sound at a temperature of $12^{\circ}C$: $v = (331+0.60~T)~m/s$ $v = [331+(0.60)~(12^{\circ}C)]~m/s$ $v = 338.2~m/s$ (b) Since the time it takes the light to reach us is negligible, we can assume that the sound wave takes 8.2 seconds to reach us. We can find the distance of the lightning strike: $d = v~t = (338.2~m/s)(8.2~s) = 2800~m = 2.8~km$ The lightning strike is $2.8~km$ away.