A wave sent out from a source is reflected back to the source in 1.0*10^-3 if the velocity of the wave is 3.0*17^8 the distance of the reflecting surface from the source is?

Answer 1

distance = speed * time
2 x in whatevers= 3*17^8 whatevers / time unit * 10^-3 sometime units

In other words ---- Without knowing units I can not help
remember the wave went twice the distance you want, there and back

Answer 2

The equation y=5sine (3x-4) where y is in millimetres and it's in second, present a wave motion. Determined the period