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Question
Find the initial velocity of a car which is stopped in 10 seconds by applying brakes. The retardation due to brakes is 2.5 m/s2.
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Solution
We have to find the initial velocity.
Final velocity as the car stops after some time, (v) = 0 m/s
Acceleration for the entire journey, (a) = –2.5 m/s2
Time taken is (t) = 10 s
Let the initial velocity be (u)
We can calculate initial velocity using 1st equation of motion as, u = v – at
So initial velocity,
u = 0 – (–2.5)(10)
⇒ u = 25 m/s
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