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Motion in One Dimension — JEE physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceJEE physicsMotion in One Dimension1 Mark
MCQ
An express train is moving with a velocity $v$. Its driver finds another train is moving on the same track in the same direction with velocity $v$. To escape collision, driver applies a retardation $a$ on the train. the minimum time of escaping collision will be
  • ✓
    $t=\frac{v_1-v_2}{a}$
  • B
    $t_1=\frac{v_1^2-v_2^2}{2}$
  • C
    None
  • D
    (A) and (B) Both
✓

Answer

Correct option: A.
$t=\frac{v_1-v_2}{a}$
As the trains are moving in the same direction. So the initial relative speed $(\left(v_1-v_2)\right)$ and by applying retardation final relative speed becomes zero.
From $v=u-a t \Rightarrow 0=\left(v_1-v_2\right)-a t \Rightarrow t=\frac{v_1-v_2}{a}$

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