Question

A vehicle of mass 1200 kg accelerates uniformly from rest to a velocity of
15 m/s in 5 seconds. It continues at this velocity for 15 seconds before decelerating uniformly at a rate of 5m/s2 to rest.

Determine the following:

(i)The acceleration

(ii)The time taken to decelerate from 15 m/s to rest

(iii)The total distance travelled

Answer 1

1. V = Vo + a*t.
15 = 0 + a*5 a = 3 m/s^2.

2. V = Vo + a*t.
0 = 15 - 5*t, t = 3 s.

3. d1 = Vo*t + 0.5a*t^2.
Vo = 0, t = 5, a = 3 m/s^2, d1 = ?.

d2 = Vo*t. Vo = 15 m/s, t = 15 s,
d2 = ?.

V^2 = Vo^2 + 2a*d3.
V = 0, Vo = 15 m/s, a = -5 m/s^2, d3 = ?.

d1+d2+d3 = Total dist.