I need to find the instantaneous velocity directly before a car collides with another at an intersection. It travels 24 metres with an acceleration of -5.39 m s2. The only time factor given is the light sequence:
Green for 45 seconds, amber for 3 seconds and red for 5 seconds before the opposing light turns green.
I don't have the velocity or time, so I don't know how I would draw a graph to figure this out.
I know the equation for Instantaneous velocity is Δy/Δx, and that I would have to draw a triangle just touching the point at which I need to find the speed of the vehicle, and then use Pythagoras. But I'm looking for speed, would instantaneous velocity still work? I have also considered the equation vi = vf + at, but again I don't have the time or velocity (neither the initial of final).
The Attempt at a Solution
If I used a displacement vs time graph, would it be the same as a velocity vs time graph? Would it give me the same (and correct) answer? Would the slope be negative, and how do I make my graph accurate enough so that my answer is?
Please, please lend me a hand, I'm so stumped.