A body is dropped from a height of $40 m$ . After it crosses half distance, the acceleration due to gravity ceases to act. The body will hit ground with velocity $(Take g = 10 m / s^{2})$ :

A

$20 m / s$

B

$10 m / s$

C

$2 m / s$

D

$15 m / s$

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Text Solution

Verified by Experts

The correct Answer is:A

Suppose $v$ be the velocity of the body after falling through half the distance. Then
$s = \frac{40}{2} = 20 m, u = 0 and g = 10 m / s^{2}$
$v^{2} = u^{2} + 2 g h = 0^{2} + 2 \times 10 \times 20$
$\Rightarrow v = 20 m / s$ .
When the acceleration due to gravity ceases to act, the body travels with the uniform velocity of $20 m / s$ . So it hits the ground with velocity $20 m / s$ .

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Updated on:21/07/2023

Class 11 PHYSICS RECTILINEAR MOTION

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