Topic: Uniformly accelerated motion relations· Kinematics

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 bef…

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 :

1. 30 cm

2. 27 cm

3. 24 cm

4. 28 cm

Doubtly Asked 30 Oct 2026 NEET UG 2023 Practice test neet Save WhatsApp Report

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Answer: 2. 27 cm

Assume a constant resistive force, so deceleration \(a\) is constant. Use \(v^2=u^2-2as\).

First 24 cm: \(\left(\dfrac u3\right)^2=u^2-2a(24)\Rightarrow 48a=\dfrac{8u^2}{9}\Rightarrow a=\dfrac{u^2}{54}\).
Total stopping distance: \(0=u^2-2aS\Rightarrow S=\dfrac{u^2}{2a}=\dfrac{u^2\times54}{2u^2}=27\) cm.

The block is 27 cm long.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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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 bef…

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