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Grade 11Mechanics

How do you solve this question? The answer is B......................................

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Profile image of Harnoor
7 Years agoGrade 11
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1 Answer

Profile image of Arun
7 Years ago
H = u² sin²A /2g .................. (1)
R=u^2 sin2A /g .........................(2)

If the projectile just has to pass the point (30,40)m then it must be the peak point of the motion.

There fore put H= 40 and R = 2 x 30

then divide H by R and obtain tanA as 8/3
then calculate sin^2 A from tanA and put in eq. 1 to obtain u as 30m/s
so ans is b, 30 m/s