Rakcsh fires a gun 160 m from a cliff. Ashok who is standing 320 m further away from the cliff hears the gunshot (i) ________ second after he sees the flash. Ashok and Rakesh will hear the echo from the cliff (ii) _______ second and (iii)_________second respectively after (iv)________ the (v)________.
Speed of sound = 320 mis (approximate)
and speed of light ` = 3 xx 10^8 m//s`

Answer

A

Explanation

Ashok sees the flash as soon as bullet is fired, where hears the gunshot after time.
`t = ("Distance")/("speed") = 320/320 = 1s`
Rakesh hears the echo after sound has travelled distance `160 + 160 m = 320 m` and Ashok hears it after distance travelled is `160 + 160 + 320 m = 640 m`
So, Ashok will hear the echo after `640/320s = 2s` of seeing the flash and 1 s after hearing the gunshot.
Rakesh will hear the echo after `(160 + 160m)/(320 m//s) = 1s`.