Suppose you are listening to an out-door live concert sitting at a distance of 150m from the speakers. Your friend is listening to the live broadcast of the concert in another country and the radio signal has to travel 3000 km. to reach him. Who will hear the music first and what will be the time difference between the two? Velocity of light = `3 xx 10^8m//s` and that of sound is `330m//s`.

Explanation

Time taken by sound to reach you
`=( 150 )/(330 ) s = 0.4546`
Time taken by the broadcasted sound (which is done by EM waves having velocity `=3 xx 10^8 `m/s)
`= ( 3000 km )/(3 xx 10^5 km //s )=( 3 xx 10^3)/(3 xx 10^5) = 10^(-2) s`
` therefore ` your friend will hear the sound first . the time difference will be
` =0.45 46 -0.01`
`= 0.4446 s`.