Question

A car is decelerating at the rate of 2 km/s square. If its initial speed is 66 km/s, how long will it take the car to come to a complete stop?

Answer 1

It will take 33 seconds to stop the car.

Step-by-step explanation:

Using the first equation of kinematics we have

`v=u+at`

where

'v' is final speed of object

'u' is initial speed of object

'a' is acceleration of object

't' is time of acceleration of object

Now since it is given that
`a=-2km/s^(2)` since acceleration is negative and
`u=66km/s`

We know that the object will stop when it's velocity reduces to zero hence in the equation above setting v = 0 we get

`0=66-2* t\\\\\therefore t=(66)/(2)=33seconds`