A body of mass 2 kg has an initial speed 5 $m{s}^{-1}$ . A force acts on it for some time in the direction of motion. The force – time graph is shown in figure. Find the final speed of the body.

Area of OAF= $\frac{1}{2}\times 2\times 4=4$
Area  of ABG F $=2\times 4=8$
Area of BGHC =  $\frac{1}{2}(4+2.5)\times 0.5=1.625$
Area of CDEH =  $2\times 2.5=5$
Total area under F-t graph = change in momentum 
 $\Rightarrow m(v-u)=18.625$
 $\Rightarrow v=\frac{18.625}{2}+5=14.3125m/\sec$