2024 AP Physics C Mechanics Set 2 Free Response Solutions

Walkthrough of the 2024 AP Physics C Mechanics Set 2 FRQs

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[AllenTsaoSTEMCoach]

Corrections

FRQ 3

Part c) the tension is still in the same spot. But the clay is now exerting a larger torque so that is why the tension is greater. My original justification was incorrect.

[richardzhu]

Thank you kind sir for saving my ap exams god bless your soul

[advancedstudy]

For FRQ 2 (e) ii. How do you know that it is not asking for an experimental procedure involving the graphed quantities to determine the relationship between sphere diameter and terminal speed?

[kavin]

at 19:07 you put a force axle on the disk pointed to the clay. Why would this be on there like this? I put a force normal on the disk vertical and opposite to gravity, and I put a force normal on the clay pointed up and to the right (tangent to the surface of the disk) as the normal force the disk is exerting on the clay. Would this work / be correct? Why or why not?

[Jake-ccie]

I was not very familiar with axles and didn't have a lot of time left and I messed up the free-body diagram then basically stated for C that the newer position's tension would be greater because of a higher radius. Needless to say, for question 3, I maybe got 2-3 points (if the radius justification even counts)

[sawyerchism]

For D i, is it asking to account for the rotational inertia of the disk and the clay? Would you use parallel axis theorem for this?

[vaskrus]

On FRQ 1 bi for the segment from 0 to t1, doesn't it switch to a constant horizontal line a little bit before t1 because t1 includes the time the block transitions to the table and is moving with constant speed v up to x1?

[chicken_nuggets]

Hi, for FRQ 3c, isn't the string still connected to the disk at Point A, not at Point B, meaning R would not be parallel to the tension force?

[RahulMohanty-ep]

Do u think this is easier than FRQ set 1? Just wondering about your opinion on which one was easier.

[jonathanpetrucelli]

For question 2. (d) if we forgot the units for the constant b do we lose a point?

[ex_ploits]

For FRQ 3 (d) i, could you have let dm=p*rdtheta*dr then integrate dtheta from 0 to 2pi and p*(r^2)*rdr from 0 to 0.3?

[alexbattikha]

would it be incorrect if the line of best fit for 2di is drawn through the origin?

[pablonerudaishidingincuba]

Where is the axle force in frq 3 coming from if there is negligible friction between the axle and the disc
Why is it assumed that this system is at rest, why does there have to be a force to counteract tension and gravity

[aldonunez]

For FRQ #3 d i) it was actually kg/m^3 so i think you had to use volume instead of area

[alexbattikha]

are there any other possibilities for what we could have graphed on the horizontal/vertical axis for 2e?

[advancedstudy]

For FRQ 3 (b) I used a cool solution involving the normal force on the clay (x and y are the real vertical and horizontal directions, not the incline directions):

Fnet y = 0 = (Mc)g - nSin(-)
---> Mcg = Nsin(-)
---> Mcg/sin(-) = N
Fnet x = 0 = T - Ncos(-)
---> Ncos(-) = T
---> (Mcg/sin(-))cos(-) = T
---> Mcgcot(-) = T

What do you think Mr.Tsao?

[vidsta]

the mcq was so difficult but this frq was a joke. frq 2 is literally just a free 15 points and frq 3 and 1 are barely any harder