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Question
A car is moving with a velocity 20 m s-1. The brakes are applied to retard it at a rate of 2 m s-2. What will be the velocity after 5 s of applying the brakes?
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Solution
Initial velocity of the car, u = 20 m/s
Retardation = 2 m/s2
Given time, t = 5 s
Let 'v' be the final velocity.
We know that, Acceleration = Rate of change of velocity/time
= (Final velocity - Initial velocity)/time
⇒ - 2 = `("v" - 20)/5`
⇒ - 2 × 5 = v - 20
⇒ - 10 = v - 20
⇒ - 10 + 20 = v
⇒ v = 10 m/s
Hence, final velocity = 10 m s-1.
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