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NTA Abhyas 2020
Exam
NTA Abhyas
Year
2020
Subject
Physics
Chapter
Motion in One Dimension

NTA Abhyas 2020 · Physics · Motion in One Dimension

A bullet emerges from a barrel of length 1. 2m with a speed of...

A bullet emerges from a barrel of length 1.2m1. 2m with a speed of 640ms−1640ms^{- 1}. Assuming constant acceleration, the approximate time that is spent in the barrel after the gun is fired is

Options

  1. A44 ms
  2. B4040 ms
  3. C400\mus400\mus
  4. D1s1s

Correct answer

A. 44 ms

Step-by-step solution

Given, s = 1.2m, v = 640\mathrm\mathrm\mathrm\mathrm\mathrm\mathrm\mathrm\mathrm\mathrm\mathrm\mathrm{ms}^{-1}, a = ? , u = 0; t = ?

We have the third equation of motion

2as=v2−u22as = v^{2} - u^{2}

2a×1.2=640×6402a \times 1.2 = 640 \times 640

Or a=8×64×1033a = \dfrac{8 \times 64 \times {10}^{3}}{3}

And by first equation of motion

v=u+atv = u + at

Or t=va=154×10−3t = \dfrac{v}{a} = \dfrac{15}{4} \times {10}^{- 3}

=3.75×10−3s≈4ms= 3.75 \times {10}^{- 3}s \approx 4ms
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