A car accelerates uniformly from $22 {\mathrm{kmh}}^{-1}$  to $45 {\mathrm{kmh}}^{-1}$  in 8s. Calculate the acceleration.

Acceleration is the rate at which velocity changes over time, both in terms of speed and direction. A point or object moving in a straight line is accelerated if it accelerates or decelerates.

We are given that

$\mathrm{u}=22 {\mathrm{kmh}}^{-1}$

    $=6.1 {\mathrm{ms}}^{-1}$

$\mathrm{v}=45 {\mathrm{kmh}}^{-1}$

    $=12.5 {\mathrm{ms}}^{-1}$

$\mathrm{t}= 8\mathrm{s}$

We know that, 

$\mathrm{a}=\frac{\mathrm{v}-\mathrm{u}}{\mathrm{t}}$

$\frac{12.5 {\mathrm{ms}}^{-1}-6.1 {\mathrm{ms}}^{-1}}{8\mathrm{s}}$

$=0.8 {\mathrm{ms}}^{-2}$