Question
Fri June 08, 2012 By: Sambhavi B
 

A ball is thrown down with velocity 5 m/s. With what velocity should another ball be thrown down after 2 seconds so that it an hit the 1st ball in 2 seconds?

Expert Reply
Fri June 08, 2012
so the 1 st ball will strike the other after travellingfor 4 s:
h=5x4+1/2  x10x4x4
  =100m
the second one thrown after 2 s b y that time the 1 st one had gone=5x2+5x2x2=30m
so the second one has to travel 100-30=70m in order to collide with the other one.
70=ut+1/2 gt
70=2u+5x4
u=25 m/s
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