Cars A and B are travelling in the same direction along a straight road. The time t is in seconds. At t = 0, car A is at rest. It accelerates at 3 ms-2 for 0⩽t⩽10

and then travels at a constant speed.

Car B travels at 15 ms-1 for

0⩽t⩽30 and then accelerates at 1 ms-2 until it reaches a

speed of 25 ms-1, after which it continues at this constant speed.

(i) Draw v-t diagrams for the motion of car A and of car B, where v is the speed in ms-1 and 0⩽t⩽80

(ii) Show that, in the first 40 seconds, car A travels 400 m further than car B.

(iii) Given that car A is 500 m behind car B at t = 0, at what value of t does car A catch up with car B?

If anyone's willing to take the time to help me with this question, I'd be super grateful. I'm really stuck on this right now.​