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A ball is thrown vertically upwards with a velocity of 19.6 \mathrm{~ms}^{-1} from the top of a tower. The ball strikes the ground after 6 \mathrm{~s}. The height from the ground up to which the ball can rise will be \left(\frac{k}{5}\right) \mathrm{m}. The value of \mathrm{k} is___________ (use \mathrm{g=9.8 \mathrm{~m} / \mathrm{s}^{2}} )

Option: 1

392


Option: 2

-


Option: 3

-


Option: 4

-


Answers (1)

best_answer

\mathrm{h\rightarrow } height of building

\mathrm{H\rightarrow } height from the ground upto which the ball can rise

From A to B

\mathrm{v^2=u^2+2 a s}

\mathrm{0=(19.6)^2+2(-9.8)(H-h)}

\mathrm{H}-\mathrm{h}=19.6 \mathrm{~m} \rightarrow \text { (1) }\\

From A to C

\mathrm{s=u t+\frac{1}{2} a t^2}

\mathrm{(-h)=(+19.6) \times 6+\frac{1}{2}(-9.8)(6)^2}

\mathrm{-h=-9.8 \times 6}

\mathrm{h=58.8 \mathrm{~m} \rightarrow 2}

\mathrm{H=h+19.6}

\mathrm{=58.8+19.6}

\mathrm{H=78.4=\frac{k}{5}}

\mathrm{ K=392}





 

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Rishi

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