A car starts moving rectilinearly

PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A car starts moving rectilinearly, first with acceleration

w=5.0\,\text{m s}^{-2}

from rest, then uniformly, and finally decelerates at the same rate

w

until it stops. The total time of motion is

\tau=25\,\text{s}

and the average velocity is

\langle v\rangle=72\,\text{km h}^{-1}

. How long does the car move uniformly?