AP Physics C: Mechanics 2018 Free Response Solutions

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[ducksfan]

My scores got released today! I got a 4 on mechanics and a 5 on e&m!! Thanks again for the wonderful videos! :)

[marcodefranque]

I got a 4 on Mech, self-studied only using your videos the day before the exam. Thank you!

[rasta]

I got 5's on both of them. Thank you for your amazing videos!

[vrowniediamond]

When you realized that you got everything wrong...

[IanXMiller]

Why isn't work done by friction included in question 3e? Especially after the previous bit asked you to think about friction.

[allisongarippo]

I just found out I got a 5. Have no idea how since everyone else in my class got either a 1 or 3, but I could not be happier

[jackysub]

@14:15, does the negative sign of the impulse disappear because we are dealing with cart 2?

[ashwinsaxena]

In part 1, is it required that you fill in the table with the values for 2H and t^2, or can you leave the rows blank and do the math in your calc?

[davidkippy]

Is it okay to look at the impulse graph and approximate the upper limit of integration as 0.16?

[ducksfan]

Oh well I think I got most of it right but I made some pretty dumb mistakes for sure. Hopefully I got a 4 but don’t see myself receiving the 5 now. I did the best I could and that’s all that matters

[epicbob]

Are you planning on releasing AP Physics C: E&M FRQ solutions?

[rishiyt]

Why is there any energy stored in the spring? The surface had negligible friction so shouldn't the second car slide freely immediately following any force, making the spring never compress. The second frq as a whole seemed very weird because of the lack of friction.

[vman]

When are you uploading the solutions for the e&m test?

[bishoyyouhanna]

was this exam for everyone in the world? i took the test in egypt and this does not seem familiar

[davidkippy]

what is a good justification for friction direction in 3d? That was part of the question.

[supriyadas]

Hi, thanks for uploading such videos which helps students to learn a lot. I was referring your video for the question 2. The approach for 2d(ii) is not correct. The answer also came wrong. The kinetic energy of the center of mass - it's has no meaning. The approach would be to (a) find the maximum force exerted by the spring, (b) find the compression at that time (c) then derive the potential energy of the spring. The answer comes a 1.46J.

[vrowniediamond]

I was just informed that my Mechanics score, along with every other student in the same test room, are cancelled and we have to retest on the late date. Guys, please don't cheat... It sucks for others too. Please. Now I have to take an 11th exam.
FML... gotta start preparing for Wednesday. So upset rn :(((

[AlikZalmover]

At least I got some questions correct, I messed up the conservation of momentum. I was going in the right direction but then I ignored the change of J. :facepalm:. Thank god there is partial credit. :)

[allisongarippo]

I just found out I got a 5. Have no idea how since everyone else in my class got either a 1 or 3, but I could not be happier