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?

Answer 1

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.