Pls answer this question.

Question

Answer 1

Area under acceleration vs time graph gives the change in velocity. 

So from give figure (graph) the change in velocity

△v= area = 1/2×base×height

​△v=1/2×4×20=40m/s

 as it stated from rest so after 20sec the  

velocity will be max=0+△v=40m/s

​

  

after t=20 sec the acceleration will become zero  

So No more change in velocity.