A student witnesses a flash of lightning and then t = 6.5 s later the student hears the associated clap of thunder. Light travels at 3.0 × 108 m/s in the air. How long, t1, in seconds did it take the light to reach the student's eyes after the flash?

Answer 1

forget speed of light in this context, so much faster than sound that basically it is infinite. All that matters is the creeping speed of sound.

6.5 s * speed of sound in air = distance

then divide that distance by 3*10^8

Answer 2

7.431x10^10