Question

4. Two tall buildings are situated 200 m apart. With
what speed must a ball be thrown horizontally
from the window 540 m above the ground in one
building, so that it will enter a window 50 m above
the ground in the other ?
(Ans. 20 ms-1)​

Answer 1

Two tall buildings are 200m apart .with what speed must a ball be thrown horizontally from the window 540 m above the ground in one building, so that it will enter a window 50m above the ground in the other?

Using Range = u^2*2h/g (using g = 9.8m/s^2)

u^2 = r*g/2h

u^2 = 400

u=20m/s

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Answer 2

$\huge\underline{\overline{\mid{\bold{\orange{Solution-}}\mid}}}$

$u\times t = 200 \implies t=\dfrac{200}{u}$

$S= ut + \dfrac{1}{2} at^2$----(1)

Value of  $S= 540-50= 490m$

Putting values in formula(1) we get

$490= \dfrac{1}{2}\times9.8 \times \dfrac{200^2}{u^2}$

$u= \dfrac{200^2}{10^2}= 20m/s^1$