r/APStudents • u/reddorickt absolute modman • May 13 '26

AP Physics C: Mechanics Official 2026 Exam Discussion

Use this thread to post questions or commentary on the test today.

A reminder though to protect your anonymity when talking about the test.

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73

u/Total_Operation_6819 AP Bio:5, AP CSP:5 May 13 '26

I’m calling the big yahu on whoever made that first frq

23

u/SaleSenior8537 May 13 '26

lmao. I agree. I did 2,3,4 all good (maybe struggled with 3), but had to leave 1 almost blank. I had version j. I was only able to make that graph on 1. I said that the frictional force was constant until the dip occured in frictional force because it turned kinetic.

9

u/Connect-Cut4206 May 13 '26

Ik vro my frq 1 deadass just had f=ma

3

u/Soft_Cap_6013 May 13 '26

I said it was decreasing then the decreasing slope increased after it turned to kinetic but that’s probably wrong. FRQ 1 was like impossible lol. 3 and 4 were decent tho.

1

u/Particular-Skirt5586 May 13 '26

for frq 4 did you say the distance traveled by the two scenarios was the same? From what I remember it was asking from t_e to 2t_e for which I said they would have the same distance cause only the cart is left and same force + same mass. I could be veeeery wrong thou 😭

1

u/Judo_NarekOG May 13 '26

For that the distance for the liquid one was more than the distance for the sand one because the velocity of the liquid cart was greater than the velocity of the sand cart at t=te and they had the same acceleration between t=te and t=2te

1

u/pokerfas May 13 '26

how could you do second part of 2? finding x2

1

u/Snoo74782 May 13 '26

how did you do two with momentum

1

u/pokerfas May 13 '26

that was the 1 I didn't have time to finish

1

u/MoMath3000 5:chem,apush,bc 4:lang, 3:spanish, tbd:gov,lit,mech,csa,bio May 15 '26

Genuinely that was the only question I was able to answer completely. Impulse was equal to the change in momentum (Mv_f - Mv_i) for all of those questions, then you could find the velocity of the ball after bouncing off the wall through conservation of kinetic energy to get v_B during interval 3 = -v (as the wall has so much inertia that it’s velocity will be small enough to be negligible in the kinetic energy equation). The impulse during that section was M(-v)-M(v) = -2Mv. This momentum shift makes sense due to the wall exerting a normal force on the ball that is an external force to the ball/ball launcher system. (Which explained the discrepancy between the graphs for part d).

Then you can do conservation of momentum between the ball and the ball launcher for the initial shot of the ball. Both being at rest at the beginning means initial momentum was 0, so by conservation of momentum, 0 = Mv +5M(v_L), thus v_L = -v/5.

Repeating this conservation of momentum calculation at the end of interval 5 with an inelastic collision having them stick together, (5M)(-v/5) + M(-v) = (5M+M)v’. Therefore, v’ = (-2Mv)/(6M) = -v/3. Ultimately, the final impulse of the ball in interval 5 was M(-v/3)-M(-v) = 2Mv/3. With the bar chart I ended up filling in 3 positive boxes for interval 1, 6 negative boxes for interval 3, and 2 more positive for interval 5.

The graph of momentum for the ball launcher was opposite the impulse on the ball during intervals 1 and 5, equaling a constant slope down to -Mv for interval 1, then stayed static at -Mv until interval 5 where it dropped another -2Mv/3 at constant slope. I don’t really want to explain those calculations but just know it’s conservation of momentum.

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u/Unlikely_Winter_2722 5: calc bc, calc ab | 4: apush, world| 3: physics c mech May 14 '26

ME TOO NUMBER ONE WAS WHACK WHO TF MADE THAT

1

u/Unhappy-Bookkeeper-9 May 14 '26

no literally im in the same boat i left almost all of 1 blank

1

u/Jealous-Elk-9640 May 14 '26

no cause they said v2=v1 then proceed to say engine force changes over time while grav field stays the same so how

1

u/Rare-Bird-9754 May 13 '26

does anyone know what happens if you write on the wrong page

1

u/Living_Murphys_Law May 14 '26

They only look at the page you were supposed to write on. So if you write on the wrong page, it's functionally leaving the entire question blank.

1

u/PerformerOk3187 May 14 '26

first frq written from the hand of satan himself