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A ball is thrown upward with an initial velocity such that it reaches the maximum height of 15m if at the same instant a stone is dropped from the height of 15m find the ratio of their distances travelled when they cross each other
Asked by 418222535371723 | 27 Aug, 2018, 09:50: PM
answered-by-expert Expert Answer
projection velocity u of the ball that is thrown to reach 15 m height is calculated using the formula, " u = begin mathsize 12px style square root of 2 g h end root end style ",
u = begin mathsize 12px style square root of 2 cross times 9.8 cross times 15 end root space equals space 17.15 space m divided by s end style
Let t be the time when the ball and stone meet at a distance S from ground.
 
S = 17.15×t - (1/2)×9.8×t2.....................(1)
15-S = (1/2)×9.8×t2 ............................(2)
 
solving (1) and (2), we get t = 0.875 s
 
Substitute t=0.875 in (1) and (2), and get the ratio  S/(15-S) = 3
Answered by Thiyagarajan K | 28 Aug, 2018, 10:24: AM

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