Consider a particle moving along a straight line, whose position as a function of time is given by
\[
s(t)=\alpha t^2-\beta t+\gamma
\]
where \(\alpha=1\,\text{m s}^{-2}\),
\(\beta=6\,\text{m s}^{-1}\) and
\(\gamma=5\,\text{m}\).
The average speed of the particle, in \(\text{m s}^{-1}\), from \(t=0\) to \(t=6\,\text{s}\) is: