Starting from rest, a subway train first accelerates to 25m/s and then begins to brake. Forty-eight seconds after starting, it is moving at 17 m/s. What is its average acceleration in this 48-s interval?
The Attempt at a Solution
I am unsure of this question here - I tried drawing the situation in a velocity vs time graph with velocity increasing from rest to 25ms^-1 and then decreasing to 17ms^-1 over 48s. However the question didn't specify the time at which it reached 25ms^-1, I attempted the question without this information but couldn't solve this question. How do you know at what point in this 48s it reaches 25ms^-1 and subsequently it's displacement?
I tried using the equation of motion for constant acceleration but could not find a suitable one.
Thus tried using the average acceleration=[itex]\Delta[/itex]X/[itex]\Delta[/itex]t in hope but I was unsuccessful there.
The answer is 0.354m/s^2