1.

A ball is projected from the ground at a speed of 10 ms^(-1)making an angle of 30^@with the horizontal. Another ball is simultaneously released from a point on the vertical line along the maximum height of the projectile. The initial height of the second ball is (Take g = 10 m s^(-2))

Answer»

6.25 m
2.5 m
3.75 m
5 m

Solution :Maximum height of projection ,`H = (u^2 sin^(2) THETA)/(2G)`
`:. H = (10)^(2)xxsin^(2) 30^(@) /(2xx10)=5/4=1.25 m`
Time for attaining maximum height, `t = (u sin theta)/g`
`:. t = (10 xx sin 30^@)/10 = 0.5 s`
`:.`Distance of VERTICAL fall in 0.5 s ,`S = 1/2 "gt"^2`
or `S=1/2 xx 10 (0.5)^(2) = 12.5 m`
`:.` Initial height of the second ball
= S + H = 12.5 + 12.5 = 2.50 m


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