Solved: PHYSICS Question for NEET | Sushrut

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NEET PHYSICSMedium

A body dropped from a height $h$ with an initial speed of zero, strikes the ground with a velocity $3 \text{ km/h}$ . Another body of the same mass is dropped from the same height $h$ with an initial speed $u' = 4 \text{ km/h}$ . Find the final velocity of the second body with which it strikes the ground.

A

3 km/h

B

4 km/h

C

5 km/h

D

12 km/h

Step-by-Step Solution

Analyze First Body: The body falls from height $h$ starting from rest ( $u_1 = 0$ ).

Using the kinematic equation $v^2 = u^2 + 2as$ with $a=g$ and $s=h$ : $v_1^2 = u_1^2 + 2gh$ $(3)^2 = 0^2 + 2gh \implies 2gh = 9$

Analyze Second Body: The second body falls from the same height $h$ but with an initial velocity $u_2 = 4 \text{ km/h}$ . The mass of the body does not affect the final velocity in free fall (neglecting air resistance).

Using the same kinematic equation for the final velocity $v_2$ : $v_2^2 = u_2^2 + 2gh$
Substitute the known values ( $u_2 = 4$ and $2gh = 9$ ): $v_2^2 = (4)^2 + 9$ $v_2^2 = 16 + 9 = 25$ $v_2 = \sqrt{25} = 5 \text{ km/h}$ .

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Solved: PHYSICS Question for NEET | Sushrut