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2. motion in straight line — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics2. motion in straight line1 Mark
MCQ
Two trains travelling on the same track are approaching each other with equal speeds of $40\, m/s$. The drivers of the trains begin to decelerate simultaneously when they are just $2.0\, km$ apart. Assuming the decelerations to be uniform and equal, the value of the deceleration to barely avoid collision should be.........$m/{s^2}$
  • A
    $11.8$
  • B
    $11.0$
  • C
    $2.1$
  • ✓
    $0.8$
✓

Answer

Correct option: D.
$0.8$
d
(d) Both trains will travel a distance of $1\, km$ before to come in rest.

In this case by using ${v^2} = {u^2} + 2as$

$ \Rightarrow 0 = {(40)^2} + 2a \times 1000$

$ \Rightarrow a = - 0.8\;m/{s^2}$

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