At a certain time a ball is thrown downward with velocity=8m/s from a building of height=40m.At the same time a stone is thrown upwards with velocity=12m/s.It is directly in line with the ball thrown from above.

Asked by Rajat Singh | 19th May, 2012, 04:22: PM

Expert Answer:

let the balls will collide after t sec.
1. let  the ball falling covers h height in t sec. nd the other ball moves up 40-h in t sec.
40-h=12t-5t2
h=8t+5t2
adding above two equ:  40=20t
t=2 sec
2. height from ground where they will collide:12t-5t2 =24-20=4m upward from the ground.

Answered by  | 21st May, 2012, 03:50: PM

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