Recent content by mancity

Doesn't friction always oppose the motion? From the clockwise rotation here, shouldn't the cylinder be moving to the right? so why are the acceleration and friction in the same direction to the right, and in the same direction as the motion? (attached image for reference)

Albeit the simple question, I am a bit confused on whether the correct answer choice is (B) or (C). When the piano is slowing down, shouldn't the force received by the piano be a bit greater than the force received by the man?

The correct solution, as given by the system, is 1.8s.

The correct answer as given by the system is III & IV. I believe small angles were indeed the intent for this problem.

So, per my understanding, would the correct answer then be III & IV? (because that is indeed an answer choice. all other answer selections only have one, i.e. I, or II, or III, or IV). Because I believe III only holds for small angles (in which we can approximate theta=sin(theta)), which would...

I am taking AP Physics 1, and currently on Unit 7 (Simple Harmonic Motion) I have attached the problem statement and the possible answer selections below. "undefined" never appeared as one of the answer choices, so I picked 0 as that was the only other answer that 'made sense' to me.

I put the answer as (IV) but that happens to be wrong (or maybe it was only one of the multiple correct answers). Here is my reasoning: I. the force is dependent on mass, but isn't always constant. II. It's not always in the same direction, it points towards the rest point. Consider a point at...

I put 0, but that is incorrect. Why is 0 an incorrect answer? This is confusing, as if the pendulum is in free fall, wouldn't there be no SHM at all?

Can someone explain that, when using the formula (Fs=1/2 kx^2) why do we use x=0.1m instead of 0.05m? Seems like a simple concept but why isn't it 0.05m (since 0.05m from equilibrium). Thanks.

The solution lists out mg(b/2)=ma(h/2) and then proceeds to solve for a. I am a bit stuck on how the initial equation is listed - why is the (b/2) swapped with the (h/2)? (namely, why isn't the equation mg(h/2)=ma(b/2)? My logic for this is y-direction and x-direction ) I feel that I am missing...

I understand that through process of elimination the only plausible solution is (E), but a question that rises up: When the ball bounces, does the velocity change from negative to positive instantly (as shown by the dotted lines) or gradually (a very small time period, but still solid line)?

Obviously the mechanical energy of the total system remains the same. But I'm having a hard time determining of the ME of the planet is constant or if it is changing.

Why do we add the two masses (3M+M=4M) and use that for M in the equation of kepler's 3rd law? Namely why is it T^2=4pi^2R^3/G(3M+M)

How would we define a value for acceleration if only the direction is changing and not the speed?

I used kinetic friction and did mgμ_k=mv^2/r. However, the solution is mgμ_s=mv^2/r. I am confused on why we consider static friction and not kinetic friction, thanks!