A car is moving along a straight road from A to B, starting from A at time t=0. Below is a graph of the car's velocity (positive direction from A to B), plotted against time.


Here is the link to the graph: https://imgur.com/a/jKX91jW


(a) How many kilometers away from A is the car at time t=6?

(b) At what time does the car change direction? Explain breifly.

(c) On the axes provided, sketch a graph of the acceleration of the car.


This problem is confusing to me. Idk how to look at velocity, accerlation on a graph. Please help. Thank you :)

 Apr 23, 2020

Let me give you a hint as to how to read the graph:


At t = 0 it is stopped (velocity is 0).

From t = 0 to t = 2 it accelerates (Its velocity is increasing)

From t = 2 to t = 3 it is travelling at a constant velocity (neither increasing nor decreasing -- on cruise control)

From t = 3 to t = 4 it is decellerating (slowing down)

At t = 4 the velocity is zero (it is stopped, but just for that moment)

From t = 4 to t = 5 it is accelerating in a negative direction (in other words, it has turned around and began driving backwards - returning)

From t = 5 to t = 6 it is decreasing its acceleration in a negative direction (its slowing down)

From t = 6 to t = 7 it is stopped (velocity is 0)

From t = 7 to t = 8 it is again accelerating.

 Apr 23, 2020

Does that mean from t=7 to t=8 it changed to a positive direction?

Paper  Apr 24, 2020

the car changes directions when the velocity graph crosses from positive to negative, or negative to positive
in this case, it looks like it changes directions when t=4 (positive to negative) and t=6 (kinda subtlely going from negative to positive)

Guest Apr 24, 2020

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