Question

A car start from rest accelerating at 6.0mls for 5secs. It continues at this speed for 25secs and then comes to a stop in 4s calculate (a). The total displacement (b). The average velocity for the whole displacement

Answer 1

You mean 6 m/s^2 I thinlk
v = 0 + a t = 6 * 5 = 30 m/s at 5 sec
d = Xi + Vi t + (1/2) a t^2 = 0 + 0 + (6/2)(25) = 75 meters from start

goes further 25 s at 30 m/s
d = 25 *30 = 750 meters more
x = 75 + 750 = 825 meters from start

stops from 30 m/s in 4 s
0 = 30 + a*4
so a = - 30/4 = - 7.5
d = 15*4 = 60 meters more
total x = 75 + 60 = 135 meters from start

how long did it take?
5 + 25 +4 = 34 seconds

Answer 2

sorry, 825 + 60 = 885