Q$3.$The velocity$-$time graph of a train traveling in a straight line from station $A$ to station $B,10$

$km$ away, is shown in Figure $1.$ The train starts from $A$ at $t=0$ and arrives at $B$ at $t=T$ hours

later. Find the acceleration of the train during the first half of the trip. $($Ans:$1000$ km$/$h$^2)$