A body is released from the top of a tower of height H . After 2s it is stopped and then instantaneously released…..

Q. A body is released from the top of a tower of height H m. After 2s it is stopped and then instantaneously released. What will be its height after next 2s (in metres)?

(a) H-5

(b) H-10

(c) H-20

(d) H-40

Ans: (d)
Sol:
In first 2 sec
$\displaystyle h = 0+ \frac{1}{2} g 2^2$
h = 20m
Again motion starts from rest

$\displaystyle h' = 0+ \frac{1}{2}g 2^2$
h’ = 20m

Height after next 2 sec
= H-40

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