2018 AP Physics C Mechanics FRQ 3

Let's roll up the hill (without slipping!) towards the finish line.

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[redvibes]

Me: "Why's the teacher making us learn moments of inertia for all these shapes? There's literally never anything more than rods on the exams"
That year's exam:

[aaronchang]

Watching this a day before the physics C exam and i gotta say, watching it makes me feel really prepared for some reason

[carlosgiovanardi]

Great work! Your explanations make physics something easy to understand!

[duckymomo]

I like rotational physics but dam this one was hard. This makes mines look easy

Triangular rod? No uniform density

Wow they kicking it up a notch

[physicsburns]

I was a little confused by the explanation you gave about the friction being up the ramp. I believe a better explanation is that since the rotational acceleration is counter clockwise as it goes up the ramp, this means the force of static friction needs to be up the ramp, because friction is what is providing the torque to slow down rotationally.

[IanXMiller]

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

[adonisborges]

Could you do a set of videos for the AP Physics 1 FRQs? I know it’s not calculus based but it would be great

[ayshaghanawi]

Great video thanks! For 3e why didn't you include the work of friction?

[neuro]

i was running out of time on this problem and after forgetting how to do (a) I got (b) and (c) and ran out of time for (d) and (e). this made it seem so easy though

[williamwen]

I forgot to add ML^2 for part b, hopefully, they will still give me points in part c for using a wrong calculation in part b. RIP.

[adiadiadi]

What kind of people attempt this in the us?? Cause here in India we get such difficult problems for IITJEE and Jee advanced which all students attempt after grade 12. I have mine tommorow. Pls do check out some jee advanced papers and solve them...i want to see your take on them

[educationalaccount]

How would you know the omega is in the counter clockwise direction? Why couldn’t it be in the other direction?

[shourjyaghosh]

When drawing the forces on the hoop-rod system, wouldn’t you also have to include kinetic friction at the point of contact? Doesn’t it provide the torque to keep the system rolling? I fail to see how the system can roll at all without some force providing a torque.

[avdeshkumar]

Bro please attempt "IIT Jee ADVANCED" 2017 paper and upload a video

[mok]

Thank u so much ! This video is awesome!

[umarpatel]

I just used (2M/L^2) and ignored the x but integrated using the right limits (0 to L) and got the answer. I also did lamda = 2M/L^2 and solved for dm. After I substituted I integrated and got the right answer. I know I didn't use the x but the x just seemed unnecessary and also because that's sort of how they did it on the 2015 Question 3 problem. It was different, so I was a bit confused but try it and you'll see it'll equal ML^2/2

[williamzhang]

Are u going to do the e&m frqs as well? Those were somewhat hard.

[duncanw]

YAY not even in C but this stuff makes tons of sense.

[ardasevmis]

I am pretty confident in my physics skill, but damn this question was tough

[nellvincervantes]

Can you do mechanical vibrations about calculating critical speed of the shaft?