Question

The brakes applied to a car produce an acceleration of 6 m s-² in the opposite direction to the motion. if the car takes 2 s to stop after the application of brakes, calculate the distance it travels during this time.

Answer 1

initial velocity = u
distance traveled = s
time = t sec = 2 s
final velocity = v = 0
deceleration = a = -6 m/s^2

v = u + a t
0 = u - 6 * 2     =>  u = 12 m/s

v^2 - u^2 = 2 a s
0 - 12^2 = - 2 * 6 * s         =>  s = 12 m

Answer 2

Answer:

initial velocity = u

distance traveled = s

time = t sec = 2 s

final velocity = v = 0

deceleration = a = -6 m/s^2

v = u + a t

0 = u - 6 * 2     =>  u = 12 m/s

v^2 - u^2 = 2 a s

0 - 12^2 = - 2 * 6 * s      

hence,  s = 12 m