InterviewSolution
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InterviewSolution
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A parojectile of mass `1kg` is projected with a velcoity of `sqrt(20)m//s` such that it strikes on the same level as the point of projection at a distance of `sqrt(3)m`. Which of the following options are incorrect:A. The maximum height reached by the projectile can be `0.25m`.B. the minimum velocity during its motion can be `sqrt(15)m//s`C. the time taken for the flight can be `sqrt((3)/(5))sec`.D. maximum potential enegry during its motion can be `6J`. |
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Answer» Correct Answer - D `R = (u^(2)sin 2 theta)/(g) rArr sqrt(3) = ((sqrt(20))^(2)sin 2 theta)/(10)` `sin 2 theta = (sqrt(3))/(2) rArr 2 theta = 60^(@), 120^(@)` `rArr theta = 30^(@), 60^(@)` (A) For `theta = 30^(@)` `H = (v^(2)sin^(2) theta)/(2g) rArr H = ((sqrt(20))^(2)(1//2)^(2))/(2xx10) = (1)/(4) = 0.75m` (B) At heghiest point of motion `u` is minimum `u_(min) = u cos theta = sqrt(20) xx cos 30^(@) = sqrt(15) m//s` (C ) `T = (2u sin theta)/(g)` For `theta = 30^(@), T = (2sqrt(20)xx(1)/(2))/(10) = (1)/(sqrt(15))` For `theta = 60^(@) , T = (2xxsqrt(20))/(10) xx (sqrt(3))/(2) = sqrt((3)/(5))sec`. (D) `U_(max) = mgH = 1 xx 10 xx 0.25 = 2.5 J` |
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