A stone is dropped from a certain height which can reach ground in 5, second . If stone is stopped a

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2.Motion in Straight Line

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A stone is dropped from a certain height which can reach the ground in $5\, second$. If the stone is stopped after $3\, second$ of its fall and then allowed to fall again, then the time taken by the stone to reach the ground for the remaining distance is........$sec$

A

$2$

B

$3$

C

$4$

D

None of these

Solution

(c) Total distance $ = \frac{1}{2}g{t^2} = \frac{{25}}{2}g$

Distance moved in 3 sec $ = \frac{9}{2}g$

Remaining distance $ = \frac{{16}}{2}g$

If $t$ is the time taken by the stone to reach the ground for the remaining distance then

$ \Rightarrow \frac{{16}}{2}g = \frac{1}{2}g{t^2} \Rightarrow t = 4\;\sec $

Standard 11

Physics

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