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# AP Calc FRQ

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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

#1
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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
#2
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Does that mean from t=7 to t=8 it changed to a positive direction?

Paper  Apr 24, 2020
#3
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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