## AAMC FL3 Chm/Phys q8

vgp1993
Posts: 18
Joined: Wed Dec 20, 2017 12:14 pm

### AAMC FL3 Chm/Phys q8

I'm having trouble following the aamc's explanation, so I was wondering if someone could help with this one.

Thanks!
NS_Tutor_Bryan
Posts: 10
Joined: Mon May 23, 2016 1:48 pm
Location: Tucson, AZ
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### Re: AAMC FL3 Chm/Phys q8

Hey,

The AAMC explanation gives us all of the information we need, but it doesn't really explain it in the clearest way.

First, the question asks for the graph of v vs. t when using the generator-braking system. Our first step is to go back to the passage to see what it had to say about the generator-braking system.

In the second paragraph of the passage we read, "Engaging the generator to the wheels puts a decelerating force...and the force declines linearly with speed."

So if you were graphing F vs. v you'd get a decreasing linear curve.

We want to remember Newton's second law: F = ma and remember that F and a are directly related to each other.

So if a graph of F vs. v would get a linearly decreasing curve, then a graph of a vs. v would do the same thing.

Now we know that acceleration, a, is decreasing.

The final step here is remembering that acceleration is v/t. And that a graph of v vs t (like in the answer choices) shows us acceleration by looking at the slope of the v vs. t curve. Here's a picture to help clarify:
Screen Shot 2018-05-23 at 8.32.31 AM.png