Question

A car moving 20 m/s in the positive x-direction slams on the brakes and stops after skidding 20 m. what was its acceleration during this period?

Answer 1

To find the acceleration of the car, we can use the following relationship:

`v_f^2 - v_i^2 = 2 aS`
where

`v_f=0` is the final speed of the car (it is zero because the car comes to rest)

`v_i=20 m/s` is the initial speed of the car

`a` is the acceleration

`S=20 m` is the distance covered

By rearranging the equation, we get:

`a= (-v_i^2)/(2 S)= (-(20 m/s)^2)/(2 (20 m)) =-10 m/s^2`
where the negative sign means it is a deceleration.