A moving train is brought to rest within 20 seconds by applying brakes. find the initial velocity, if the retardation due to brake

2 thoughts on “A moving train is brought to rest within 20 seconds by applying brakes. find the initial velocity, if the retardation due to brake”

1. Understanding the question: This question says that we have to find out the initial velocity if a moving train is brought to rest within 20 seconds by applying brakes. And the retardation due to brakes is [tex]{\sf{2 \: ms^{-2}}}[/tex] Let’s do it!

   Given that:

   • Final velocity = [tex]{\sf{0 \: ms^{-1}}}[/tex]
   • Acceleration = [tex]{\sf{-2 \: ms^{-2}}}[/tex]
   • Time taken = 20 seconds

   Don’t be confused!

   • Final velocity came as zero because moving train is brought to rest.

   • Acceleration came in negative beacuse the train retards.

   To calculate:

   • The initial velocity

   Solution:

   • The initial velocity = 40 m/s

   Using concept:

   • First law of motion

   Using formula:

   • v = u + at

   Where, v denotes final velocity , u denotes initial velocity , a denotes acceleration and t denotes time.

   Full Solution:

   → v = u + at

   → 0 = u + (-2)(20)

   → 0 = u + (-40)

   → 0 = u – 40

   → 0 + 40 = u

   → 40 = u

   → u = 40 m/s

   → Initial velocity = 40 m/s

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2. Answer:

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   Step-by-step explanation:

   v = u + at

   0 = u + (-2)(20)

   0 = u + (-40)

   0 = u – 40

   0 + 40 = u

   40 = u

   u = 40 m/s

   Initial velocity = 40 m/s

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