Calculate how long it would take a car traveling at 30m/s to come to a complete stop if it has a constant deceleration of 4m/s²

7.5s

Explanation:

Given parameters:

Velocity  = 30m/s

Deceleration  = 4m/s²

Unknown:

Time it takes for the car to come to complete rest  = ?

Solution:

 To solve this problem, we use the kinematics expression below:

        v  = u + at

 Since this is a deceleration

         v  = u - at

v is the final velocity

u is the initial velocity

a is the acceleration

t is the time taken

         v - u  = -at

         0  - 30  = -4 x t

              -30  = -4t

               t  = 7.5s