@xybear Could you say that Vavg can’t possibly vary linearly with g(sin theta) to support your claim that the equation doesn’t make physical sense?
Also for free response number 4 part b, does the current increase, decrease, or stay the same?
For the ones you had to plug in two answers for, did you guys get AD for a lot of them?
@dharma108 current through a would decrease I believe
For that weird block/wheel one I said that the block would reach the ground with the greatest speed because it has negligible friction. Is that right?
@lrylander crap I put it would stay the same.
@lrylander same here
@Walaoeh I agree that the block had a greater speed. I think friction is part of it, however in my response I emphasized that the wheel would use up some of its KE as rotational kinetic energy whereas with the block it would be purely translational Kinetic Energy
@lrylander Yeah, I didn’t realize this until it was too late… Hopefully they’ll still give points for using friction as an explanation.
can confirm that Irylander’s answer and justification are correct :>
@dharma108 “Also for free response number 4 part b, does the current increase, decrease, or stay the same?”
decrease; overall resistance increases, so the current drawn from the battery decreases.
@dharma108 @lrylander I also put friction, but I tossed in rotational motion at the very end, thank goodness.
I calculated my potential score and I’m right at a high 4 or low 5 :-S
@lrylander How did you calculate your score?
@xybear Thanks! I really hope I get a 5…
@Walaoeh Yes! I had D in all of mine, like 3-4 with A and one with B.
What about the graph for the 3rd frq?
My opinion on multiple choice: Too heavy focus on 2-3 topics for the majority. Predicted score: 33-37/50
FRQ 1: I misread to solve for accel so if it’s a two point question I’ll get the point for solving for frictional. Overall an easy problem if you understood basic rotational motion vs translational motion Predicted: 5/6 out of 7.
FRQ 2: Fair design question. Easier to understand in comparison to last years circuit experiment. Testing change in KE through different in experiment velocity (d/t) on descent and ascent. Easiest thing to violate was make ascent h higher than the allowed max due to g (9.8). Predicted: 9/10 out of 12
FRQ 3: Odd question. Definitely never seen anything like it but seemed to be a standard energy question for the first half of the problem before the equation. Part 2 on the equation/data was definitely harder. I believe the equation didn’t fit the data bc if you linear both ways. You get a +b value which makes no sense of you have no mass in relation to the equation. Then the equation didn’t make sense physically due to the numerator being (Mgsinø=net force)/distance= not Velocity
Predicted score (assuming the equation doesn’t fit data: 11 or 12. Assuming I got it wrong: 8-10 of 12.)
FRQ 4: The AP board was saying in this question: Here’s 7 free easy points if you have any clue about what your physics teacher taught two weeks before the AP test. Tbh. They didn’t ask for much in this problem. Just simple theoretical current under constant voltage or emf. They didn’t even ask about the bulb’s power like they did on the 25 min question for AP physics 2 last year (which btw was like a ap physics 1 problem except for part ©.) Predicted Score: 7
FRQ 5: Not going to lie. This one is a tricky one to explain. If you look at AP physics 1 2015 question 5. It’s essentially asking about why the equation they gave last year is true as tension goes up. (A quick answer for those confused: Higher tension means more resistance to higher amplitude in comparison to Q. But also a higher restoring force and it’ll have an “acceleration” causing it to “snap” back to equilibrium faster than a looser spring. The Colorado phet lab illustrates this concept.)
Predicted Score: 5/6 of 7. (I never mentioned the restoring force but I described it so I’ll prolly miss a point of two from my explanations)
Predicted final score: Definite 4. Average probability of 5.
Any questions on any of the problem. Mention me and I can discuss my thoughts on a possible solution. Thanks.
@Dayruiner what are you talking about with FRQ 5? No idea what you mean with resistance and restoring force. The tension is higher at P because it’s supporting more of the rope’s weight (everything underneath P) than Q is (everything underneath Q). You can infer that velocity of waves is faster on higher tension because the wavelength at P was bigger than at Q, and according to v=λf, v increases (frequency given by oscillator is constant).
EDIT: I would also say that the graph did match the data in FRQ3, because it showed that when M increased, Vavg increased, just like her equation.