How can you calculate the acceleration from velocity-time graph?

Suggest what kind of motion of a body is represented by the graphs given below:

Suggest what kind of motion of a body is represented by the graph given below:

A body is initially having a velocity u. it is acted upon by uniform acceleration $\text{'}\mathrm{a}\text{'}$ for $\mathrm{t}$ seconds such that it picks up a final velocity of $\text{'}\mathrm{v}\text{'}$ and in doing so covers a distance $\text{'}\mathrm{s}\text{'}$. Represent the above statement graphically and establish;

 $$\begin{gathered} \left(\mathrm{i}\right) \mathrm{v}=\mathrm{u}+\mathrm{at} \\ \left(\mathrm{ii}\right) \mathrm{s}=\mathrm{ut}+\frac{1}{2}{\mathrm{at}}^2 \end{gathered}$$ 

Suggest real life examples where the motion of a body similar to that represented by the following velocity-time graphs: