A bullet from a gun is fired on a rectangular wooden block with velocity u . When bullet travels 24 cm through the block along its length horizontally, velocity of bullet becomes u/3 . Then it further penetrates into the block in the same direction before coming to rest exactly at the other end of the block. The total length of the block is :

Physics · Work, Power & Energy

NEET (UG) 2023 — Question 33

A bullet from a gun is fired on a rectangular wooden block with velocity $u$ . When bullet travels 24 cm through the block along its length horizontally, velocity of bullet becomes $\frac{u}{3}$ . Then it further penetrates into the block in the same direction before coming to rest exactly at the other end of the block. The total length of the block is :

Option A:
24 cm
Option B:
28 cm
Option C:
30 cm
Option D:
27 cm
Correct

Answer: D

Step-by-step solution

between 1 to 2

\begin{aligned} & \left(\frac{u}{3}\right)^2=u^2-2 a \times 24 \\ & \Rightarrow 2 a(24)=\frac{8 u^2}{9} \end{aligned}

between 2 to 3

0=\left(\frac{u}{3}\right)^2-2 a s

From equation (I) and (II)

\begin{aligned} & 2 a s=\frac{2 a(24)}{8} \\ & s=3 \mathrm{~cm} \end{aligned}

Length of wooden block is $24+3=27 \mathrm{~cm}$

Answer key and solution verified before publishing.

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Exam: NEET (UG) 2023
Paper: 2023 paper
Subject: Physics
Chapter: Work, Power & Energy
Topic: Kinetic Energy and Work-Energy Theorem

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Answer: D

Step-by-step solution

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