When Will the Cars Collide? A Problem in Accelerated Linear Motion

[mcintyre_ie]

If anybody could offer any help with this id be eternally gratefull

Two cars A and B, each 5m in length, travel with constant velocity 20 m/s along a straight level road. The front of car A is 15m directly behind the rear of car B. Immediately on reaching a point P, each car decelerates at 4m/s^2.
1) Show that A collides with B
2) At what distance from P does the collision occur?
3) Show the motion of both cars on the same speed-time graph.

Thanks in advance

 

[mathman]

The cars will collide at the point where they stop (B stops first and A stops at the same point). I'll leave the rest as an exercise in elementary calculus.