A Man throws a ball towards a wall which is 74m away. After the ball hitting the wall he runs towards the wall and hears sound after 0.2s.The temperature was #30^@C#.what was the velocity of man?

1 Answer
A08
Apr 9, 2018

Let us assume the man runs towards the wall with a constant speed of #v#.
Take speed of sound at #30^@C# as #349.5\ ms^-1#.

Distance covered by man in #0.2\ s=0.2v#
Distance covered by sound in #0.2\ s=0.2xx349.5#

Sum of these two distances must be equal to the initial distance between man and the wall. Therefore, we have

#0.2v+0.2xx349.5=74#
#=>v=(74-69.9)/0.2#
#=>v=20.5\ ms^-1#

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