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A ball is thown at angle `theta` and another ball is thrown at angle `(90^(@)- theta)` with the horizontal direction from the same point each with speeds of 40 m/s. The second ball reaches 50 m higher than the first ball. Find the individual heights. ` g= 10 m//s^(2)` |
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Answer» For the first ball, angle of projection `=theta`, velocity of projection, `u=40 ms^(-1)` Let h be the maximum height attained by it. As maximum height `=(u^(2)sin^(2)theta)/(2g) therefore h=((40)^(2)sin^(2)theta)/(2xx10)`....(1) For second ball, Angle of projection `-(90^(@)-theta)`. velocity of projection, `u=40ms^(-1)` Maximum height reached `=(h+50)m` `therefore h+50=(u^(2)sin^(2)(90^(@)-theta))/(2g)=((40)^(2)cos^(2)theta)/(2xx10)` .....(2) By adding (1) and (2), `2h+50=((40)^(2))/(2xx10)xx(sin^(2)theta+cos^(2)theta)=((40)^(2))/(2xx10)=80rArr 2h=80-50=30rArrh=15m` Height of the first ball, h=15m `&` Height of the second ball, =h+50=15+50=65m |
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