# Search results

1. ### Atwood's Machine using Angular Momentum

:O It all makes sense. You are a genius. Thanks a ton!
2. ### Atwood's Machine using Angular Momentum

Sorry about that. I did mess up on the algebra, but I still got a different acceleration:
3. ### Atwood's Machine using Angular Momentum

Oh. Then why can't we solve the first problem using angular momentum when treating the Atwood's machine as three different systems? Actually, isn't that what I did when I replaced m_1g and m_2g with T_1=m_1(g−a) and T_2=m_2(g+a), respectively. Consequently, for linear acceleration I got...
4. ### Atwood's Machine using Angular Momentum

Ah that kind of makes sense. I'll sleep on it tonight. :) One more question: can we solve the first problem using angular momentum like done above but treat the masses as different systems? You can't solve the second problem using tension and choosing the entire Atwood's machine as the system...
5. ### Does close systems really exist?

He never said it was isolated. he said it was closed.
6. ### Atwood's Machine using Angular Momentum

That makes sense but this doesn't explain (at least not to me) why the torques are the forces of gravity and not the tension. I have no problem with the angular momentum part of the question, it's just the torques. This was my first surmise but why didn't the tensions cancel in the second...
7. ### Atwood's Machine using Angular Momentum

Hey everyone. I'm kind of stumped on this example from my textbook. It uses angular momentum to solve an Atwood's machine problem. Here is how the problem and the solution goes: My question is, why does the book use force of gravity as the force acting on the pulley instead of the...
8. ### Torricelli's Law

Oh wow I didn't think about the fact that if there is a hole, the pressure at the bottom of the tank (more specifically, the small hole) is not P=pgh. Thanks!
9. ### Torricelli's Law

Hey I have a question on the derivation of Torricelli's Law. Bernoulli's Equation states the following: Now let's say that the left side of the equation is the top of the tank and the right side of the equation is the bottom of the tank. The origin is at the bottom of the tank. We can...
10. ### Swinging a ruler around a pen

Hey everyone. So I was bored and I started swinging my ruler around my pencil (my ruler has a little hole where my pencil can be inserted into). Then I remembered we talked about why the ruler starts to go up the pencil if frequency increases in my physics class last year. The thing is, I can't...
11. ### What is this object called? It deals with Pressure.

Hi. When I took AP Physics last year, my teacher demonstrated the power of pressure by this object. It looked like a lid. It was rubber. You put the lid on a wooden desk, turn the nod on top of the lid, and try pulling the lid off the desk without sliding the lid. I forgot the name of this...
12. ### Speed of the electron after the collision

Conservation of Energy: KE_e_i = KE_{e_{f}} + E_{atom} assuming that the atom is initially at rest.
13. ### Tension and Static Friction

Just to make sure, is this how it looks? http://i180.photobucket.com/albums/x314/Lil_Aziz1/Untitled-21.png
14. ### Heavy and Light Nuclei

um which ones are more stable? How is one more massive than the other (Do heavy nuclei have more protons or nuetrons)?
15. ### Heavy and Light Nuclei

What's the difference between them?
16. ### How much work was done to overcome friction?

oh! so to get the work done by friction, one would subtract 200*1.5 from (10)(3). Thanks a ton! To get the efficiency, one would just do (mgh)/(F*d)
17. ### How much work was done to overcome friction?

ok so the 200N is the force with friction. how am i suppose to find the force without friction? Isn't the force without friction greater than 200 if you think about it intuitively? If friction is not acting on the box, the only force acting on the box is the x-component of gravity; thus, F =...
18. ### How much work was done to overcome friction?

Force * distance. right?
19. ### How much work was done to overcome friction?

Homework Statement NO CALCULATOR ALLOWED. a 50-kilogram box is pushed up a 1.5m-meter incline with an effort of 200 Newtons. The top of the incline is 0.5 meter above the ground. How much work was done to overcome friction? (A) 55J (B) 75J (C) 245J (D) 300J (E) 490J The inclination in the...
20. ### Single-Slit Diffraction

Though I'd bump this thread since I've gotten no reply in two days.
21. ### Single-Slit Diffraction

Hi everyone. I need help comprehending single slit diffraction. I am using the textbook: College Physics by Serway / Vuille 8th Edition. This is what it says: "To analyze the diffraction pattern, it's convenient to divide the slit into halves, as in Figure 24.17 (picture below). All the waves...