AP Physics 1 2015 Free Response Solutions

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[milty]

Thank you so much for making this video! I now think I did better on the frq's than I thought I did right after the test! Thanks for all your videos, they helped me a lot this year!

[krish-syf]

For the question regarding the energy graphs, why is the potential energy 0 from equilibrium position to 3d? The block still has momentum at x= 0. The block and the spring will be in contact throughout the duration of the motion. Right? Thus the kinetic energy of the block will still be quadratic from x = 0 to 3d. Also, since the block is always in contact with the spring the elastic potential energy from x = 0 to 3d is non-zero. I'm not sure why the elastic potential energy is zero and why the kinetic energy is linear from x = 0 to 3d.

[krish-syf]

because both friction and the spring force are both doing work on the block
Change in kinetic energy (from 0 to 3d) = -1/2d^2 + Fd
thus final KE as a function of displacement = -1/2d^2 + FD + KE (at D = 0). The function is quadratic not linear. Can you please clarify?

[xichen]

Mr. Fullerton, what raw score do you think we need to get in order to get a 5?

[planetpeter]

Hey Dan!
In 1(c), the acceleration would also be decreased if it asked about block 1, correct?

[financialkevin]

Hey Mr.Fullerton I'm currently doing some homework on Vertical acceleration, Horizontal acceleration and Universal gravitation. After what my teacher taught me I still don't get it is there any chance that I could show you the problems?

[gabbyarredondo]

Hey Dan, for part 2 of the first frq; T was first in T - m1g because it was bigger right? 2:41

[planetpeter]

Hey Dan!
Great videos. In 2b(i), how come you don't have to specify the case where more current goes in than our or vice versa -- how come they only required the equality case?

[naseemsalim]

Referring to the second question asked by the students in question 2: what's the difference in answers to that question when comparing a series and a parallel circuit (if any difference)?

[KavanShahthegreatest]

In the question 5(a), could the frequencies be different because the wires were made up of different materials and hence had different densities?

[johnlin]

will you be doing this for the 2016 frq? its out now :D

[planetpeter]

Hey, for part 1(c), what's the intuition behind why the tension of the string on block 2 is greater?