Motion In A Straight Line Ques 2

2. A ball is thrown vertically upward. It has a speed of $10 $ $\mathrm{m} / \mathrm{sec}$ when it has reached one half of its maximum height. How high does the ball rise?

[2005, 2001]

Take $g=10 $ $\mathrm{m} / \mathrm{s}^2$.

(a) $10 $ $\mathrm{m}$

(b) $5 $ $\mathrm{m}$

(c) $15$ $ \mathrm{m}$

(d) $20$ $ \mathrm{m}$

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Answer:

Correct Answer: 2.(a)

Solution: (a) For part $A B$

From $3rd$ equation of motion

$v^2=u^2-2 \mathrm{gH}$

$ \begin{aligned} & 0=u^2-2 \mathrm{g}(\mathrm{H} / 2)=u^2-\mathrm{gH} \\ & \mathrm{H}=\frac{u^2}{g}=\frac{10^2}{10}=10 \mathrm{m} \end{aligned} $