Work Done by Variable Force

A body moves from point $A$ to point $B$ under the action of a force varying in magnitude as shown in the force-displacement graph. Find the total work done by the force. 

When a particle is displaced from a position $\overrightarrow{r_1}=(2\hat{\mathrm{i}}+2\hat{\mathrm{j}}) \mathrm{m}$ to $\overrightarrow{r_2}=(4\hat{\mathrm{i}}+5\hat{\mathrm{j}}) \mathrm{m}$, then the work done by a force $\overrightarrow{F}=(3x^2\hat{\mathrm{i}}+2y\hat{\mathrm{j}}) \mathrm{N}$ on the particle is 

A force $\overrightarrow{F}=(3t \hat{\mathrm{i}}+5 \hat{\mathrm{j}}) \mathrm{N}$ acts on a body due to which its position varies as $\overrightarrow{s}=(2t^2 \widehat{ \mathrm{i}} - 5\hat{\mathrm{j}} )$. The work done by this force in the initial $2 \mathrm{s}$ is