(i) Since acceleration is the rate of change of velocity, it is given by the slope of the velocity time curve. Here the slope is greatest between ¾ and 1 hour.
Change in the velocity in this interval = (60-20) km h⁻¹
.·. Acceleration in this interval = (60-20)/(1-(3/4)) km h⁻²
= 160 km h⁻²
(ii) Distance travelled during this interval is given by s=ut+1/2at²
=20(1/4)+1/2(160)(1/4)²
=10km