This has something to do with graphing (speed time graph) so I suspect this is the right forum.
Question: Two stations A and B are 495m apart. A train starts from A and accelerates uniformly for 15s to a speed of which it maintains until it is 90m from B. Sketch a speed-time graph to show the motion of the train. Find the magnitude of the acceleration and retardation and the total time the journey takes.
I'm stuck on the magnitude of acceleration =\ .
Not quite true . THe train accelerates until a point 90 m before B . Then from here , the train decelerates until station B .
So for acceleration , you know s=405 m , u=54 km/h (convert this to m/s) , and t=15 s
so by s=ut+1/2at^2 , you can find a .
Now for deceleration ,
s=90 , u=54 km/h (again , do the conversion) , v=0
use , you should get a negative value for a since its deceleration.