Question

A bus moving with a speed of 54 km/h . on applying brakes, it stopped in 8s .calculate the acceleration and the distance travelled before stopping

please help in solving solution

Answer 1

hey there !!!!

  Initial Speed  (u)= 54 km /hr = 54 *1000 m / 3600 s = 54*5/18 = 15 m/s
         ( 1km = 1000 m and 1hr = 60 mins = 60*60 seconds = 3600 seconds)
        Time = 8 seconds
       Final Velocity (V) = 0
 we know that ,
         v = u + at
         0 = 15 + a*8
       0 = 15 + 8a
       a= -15/8 m/s²
   Therefore , acceleration is -15/8 m/s²
also ,
           S = ut+1/2at²
           S = 15*8² + 1/2 *(-15/8)*8²
              =15*64 - 15*4
             = 15(64 - 4)
             =15(60)
             S=900 m
hence Stopping Distance traveled before stopping is 900m.

hope that helps !!
☺☺ himanshu Jha .☺☺