Rahul is standing on the street and wants to throw an $8 k g$ book up to his friend who is leaning out of a window $5 m$ above street level. With what velocity Rahul must throw the book so that it reaches his friend in the window?

5 m / s

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8 m / s

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10 m / s

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40 m / s

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50 m / s

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Solution

The correct option is B $10 m / s$
Given : $S = 5$ m $v = 0$ m/s $a = - g = - 10 m / s^{2}$
Let the initial velocity of the book be $u$ .
Using $v^{2} - u^{2} = 2 a S$
$∴$ $0 - u^{2} = 2 (- 10) \times 5$
$⟹ u = 10$ $m / s$

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A boy standing on a stationary lift (open from above) throws a ball upwards with the maximum initial speed $= 49 m / s$ .
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b) If the lift starts moving up with a uniform speed of $5 m / s$ and he again throws the ball , how long does it take to return to his hands ?

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Rahul is standing on the street and wants to throw an 8kg book up to his friend who is leaning out of a window 5m above street level. With what velocity Rahul must throw the book so that it reaches his friend in the window?

The correct option is B 10m/sGiven : S=5 m v=0 m/s a=−g=−10m/s2Let the initial velocity of the book be u.Using v2−u2=2aS∴ 0−u2=2(−10)×5 ⟹u=10 m/s

Rahul is standing on the street and wants to throw an $8 k g$ book up to his friend who is leaning out of a window $5 m$ above street level. With what velocity Rahul must throw the book so that it reaches his friend in the window?

The correct option is B $10 m / s$
Given : $S = 5$ m $v = 0$ m/s $a = - g = - 10 m / s^{2}$
Let the initial velocity of the book be $u$ .
Using $v^{2} - u^{2} = 2 a S$
$∴$ $0 - u^{2} = 2 (- 10) \times 5$
$⟹ u = 10$ $m / s$