# Search results

1. ### Anybody know where I can find more logic problems?

I would like to practice logic thinking more. The sort of problems I'm talking about are like this: Define two constraints, which relates the variables x and y to v such that if either x or y is 1 then v is forced to be 1. Where the answer is then: x ≤ v y ≤ v Does anybody know where I can...
2. ### Do pretty girls not care about a guy's education?

Yeah but what if you suddenly get bad at playing Smash Bros. and no longer cna win tournament prizes, then you have no income and no education to rely on? Wouldn't it be more wise for girls to choose a guy that has a steady income? A guy who is actually smart?
3. ### Do pretty girls not care about a guy's education?

My mom always used to tell me that girls are attracted to guys with a good education but now I'm thinking it was something she just told to get me to study. I've noticed that I have no more luck with girls than my friends who don't have an education past high school and that in many cases, guys...
4. ### Regarding a bimorph's structure

Are you sure? I've tried searching for it many places but I just can't find anything about it.
5. ### Regarding a bimorph's structure

Can anyone explain to me why a bimorph has a metal in between the two piezo-layers?
6. ### Is the mass flow rate in a regenerative vapor power cycle constant?

Does the mass flow rate differ depending on whether it's after the feedwater heaters or before the turbines or is it just constant throughout the entire system?
7. ### Is there a guide for the properties of ideal gasses?

Oh, I see. Actually when I looked at my notes I found a place where it says the change in pressure is zero. It's just a lot of information to keep up with. Thanks! :)
8. ### Is there a guide for the properties of ideal gasses?

What I'm asking for is if there is a guide for the properties of processes like isochoric, isobaric, isothermal and adiabatic. For instance, a comprehensive guide that tells me that the pressure in an isobaric expansion is the same before and after, etc. If there isn't, does anybody have any...

Thank you!
10. ### Figuring out the potential energy

Ahh, I mixed them up. Ok I changed the drawing so now d is the distance the mass moves up and x is the distance the roller moves down: So I have: h' = x * sin(theta) And: h = d * sin(beta) And... I know that the distance that both the mass and roller travels are equal to each other: x = d...
11. ### Figuring out the potential energy

Alright let me see... I drew this line in the drawing: The number "2" on the left indicates the final position where the cylinder is when the box is at the top. If we assume that "d" is the distance down the triangle that the cylinder rolls and if h' is the height of the potential energy for...
12. ### Figuring out the potential energy

Homework Statement A cylinder with mass M and radius R and moment of inertia I is standing on a rough surface (the left part of the triangle). A box with mass m is standing on a smooth surface (right part of the triangle). The cylinger and box is connected by a massless rope over a massless...
13. ### In which direction does the friction on the wheel go?

Oh I see. If the situation was where the wheel was standing at rest and didn't move then the friction force would be to the right to prevent it from rolling but since the wheel is rolling that means our friction force is to the left, correct?
14. ### In which direction does the friction on the wheel go?

Homework Statement The following wheel consists of an outer ring (R) and an inner ring (r). The wheel moves clockwise by a force F applied to the inner ring as shown in the picture to make the wheel roll. Draw the friction force. Homework Equations Nothing The Attempt at a Solution I could...
15. ### Calculating the average force of a molecule in a vessel

Homework Statement Suppose an oxygen molecule traveling at the speed of 484 m/s bounces back and forth between opposite sides of a cubical vessel 0.1 m on a side. What is the average force the molecule exerts on one of the walls of the container? Homework Equations F=p/t The Attempt at a...
16. ### I don't understand the concept of phase diagrams?

Let's use the material brass as an example. My problem is that I have no understanding of the concept of "phases". In the phase diagram for brass, we have α, β, γ, δ, ε, and η phases as well as the liquid phase (L). My question is, how do I interpret these phases? What is the difference...
17. ### Calculating the change in entropy, did I calculate correctly?

Homework Statement A 3.5 kg block of cobber at 100 degrees celsius (373 K) is put in 0.8 kg water at 0 degrees celsius (273 K). The equilibrium temperature is 30 degrees celsius (303 K). Calculate the change of entropy for the system of cobber and water. Homework Equations ΔS=\frac{Q}{T}...
18. ### How to tell the difference between reversible and irreversible process

No you can not reverse the process so it is an irreversible process. Was that correct?
19. ### How to tell the difference between reversible and irreversible process

My guess is no because the steel block cannot spontaneously go back to 100 degrees celsius after it has been cooled so it is an irreversible process?
20. ### How to tell the difference between reversible and irreversible process

Imagine a rigid block of steel at 100 degrees celsius which is inserted into water at 0 degrees celsius. They then both get an equilibrium temperature. How can I tell whether this is a reversible or irreversible process? What is the argumentation?
21. ### Finding the volume of air in a box when it's lowered into water?

But what about V_0=2.5? Am I not supposed to use that for anything?
22. ### Finding the volume of air in a box when it's lowered into water?

The 3.0 is the volume for the air and the box. The 2.5 is only for the air. In the ideal gas law what do I use for n and T?
23. ### Finding the volume of air in a box when it's lowered into water?

Homework Statement A box that is open at the bottom is lowered into the sea (density like water). The outer volume of the box and the air inside it is V_{out}=3 m^3. The moment the box touches the sea surface the air inside it gets trapped and has a volume at V_0=2.5 m^3 and a pressure at...
24. ### Not sure if I calculated this correctly (Find the final temperature)

Oh yes, you're right. Then I get: T=\frac{2\cdot 4190\cdot 20+2\cdot 910\cdot 600-2256000\cdot 2}{2\cdot 4190+2\cdot 910}=-319 °C That's clearly not correct though so I'm assuming this isn't the correct method that I'm using. How do you know the final temperature is 100 °C? Is it because it...
25. ### Not sure if I calculated this correctly (Find the final temperature)

I just realized that I miscalculated on both equations. Let me try again: If the cylinder was made of copper: I assume that the water does not boil so the final temperature will be less than 100 °C (boiling point of water). T=\frac{2\cdot 4190\cdot 20+2\cdot 390\cdot 600}{2\cdot 4190+2\cdot...
26. ### Not sure if I calculated this correctly (Find the final temperature)

Did I solve this correctly? I'm not sure if my method is correct. Homework Statement A metal cylinder with the specific heat c_{cylinder} and mass m_{cylinder} is warmed up to temperature T_{cylinder} and then cooled down by putting it into water which has the temperature T_{water} and mass...
27. ### Finding the momentum after a collision

According to my calculations: Before: L=Mul After: L=(2Ml^2+1/3ml^2)v/l
28. ### Finding the momentum after a collision

It's half. So that would make the linear momentum after the collision: p=2Mv+m\frac{v}{2}?
29. ### Finding the momentum after a collision

I found my v to: v=\frac{u}{2+\frac{m}{3M}} The CM velocity would be: v_{CM}=\frac{2mv}{2m}=v So the velocity of CM would be equal to the speed of the balls?
30. ### Finding the momentum after a collision

That is I=\frac{1}{3}ml^2 So then I have L=\frac{1}{3}ml^2\frac{v}{l} But how do I go from the angular momentum to the momentum? I need to incorporate it into p=mv somehow but I haven't been able to figure it out.
31. ### Finding the momentum after a collision

Is it L=I\omega? If my angular momentum is conserved, that means the angular momentum before and after are equal each other. The angular momentum before the collision was L=Mul so that has to be equal to the angular momentum after the collision: Mul=I\frac{v}{l} Then I can find an...
32. ### What have I done wrong? (torque and angular momentum)

That's it! Now the answer is correct, thanks! :)
33. ### Finding the momentum after a collision

The incoming ball's angular momentum about the rod's axis before collision is L=Mul The two ball's angular momentum after collision is L=2Mvl The rod moves at velocity v and its angular velocity is \omega=\frac{v}{l} Therefore the momentum before the collision is just the incoming ball...
34. ### Finding the momentum after a collision

But I'm still confused as to how I find the momentum after the collision. I know that the equation for momentum is: p=mv I know that for the balls it is simply their mass multiplied by their velocity which are all known variables. But I also have to take the rod's momentum into...
35. ### What have I done wrong? (torque and angular momentum)

[SOLVED] What have I done wrong? (torque and angular momentum) Homework Statement A billiardball is hit from rest by the cue at height "h" from the table with a force F in the time interval Δt. The mass M and radius R of the ball is known as well as the moment of inertia which is...
36. ### Finding the momentum after a collision

I would take moment about the rods axis, the point where it is attached to the ceiling, right?
37. ### Finding the momentum after a collision

Is it the angular momentum?
38. ### Finding the momentum after a collision

Im pretty sure it is the angular momentum about the rods axis, right?
39. ### Finding the momentum after a collision

The momentum before the collision would be the ball with the velocity u: p=mu Where m is the known mass of the ball.
40. ### Finding the momentum after a collision

Homework Statement A ball is attached to one end of a rod. A second ball hits the ball with velocity u. The collision is inelastic and both balls after the collision travel together with a new velocity v. The rod is attached to the ceiling at a point with no friction. The moment of inertia...
41. ### What is conserved in the system?

Is it correct to assume that there is conservation of angular momentum about the CM? Since the added weight (when the two ball join together) thus balance out the uneven weight by moving the center of mass thus the rotation has angular momentum conservation?
42. ### What is conserved in the system?

The moment of inertia? It makes it harder for the rod to rotate around the point on the ceiling?
43. ### What is conserved in the system?

Homework Statement A ball is attached to a rod at one end. The rod rotates about a point at the other end. A second ball hits the first ball with a horizontal velocity u, and then the two balls travel together with the same horizontal velocity v. The collision is inelastic. What is...
44. ### Uniform circular motion and angular momentum?

Oh yes, now I see it. I have 3 equations and 3 unknowns. I don't know why I didn't see that before. Thank you both for your help!
45. ### Uniform circular motion and angular momentum?

Originally I had my speed: M\cdot g=m \frac{v^2}{R} After the water was added, I have: (M+M_{water})\cdot g=m \frac{v'^2}{R'} But I'm not sure how to combine these equations with L = mv'R'? Can you explain that?
46. ### Uniform circular motion and angular momentum?

My guess is that it got bigger? For a particle, we have that L=mvR Since the angular momentum is conserved, that means that the angular moment before and after is adequate: mvR=mvr Where R is the radius before water was added and r is the radius after water is added (the radius that...
47. ### Uniform circular motion and angular momentum?

Do you mean like this: (M+M_{water})\cdot g=m \frac{v^2}{R}
48. ### Uniform circular motion and angular momentum?

I'm a little bit confused by the equation for angular momentum that you wrote. In my textbook, it writes two different formulas. Angular momentum for a particle: L=r \times p = r \times mv Angular momentum for a rigid body rotating about axis of symmetry: L=I\omega I'm assuming I...
49. ### Uniform circular motion and angular momentum?

The force needed to cause a circular motion is ? It is based on Newton's second law, am I right? The radial acceleration combined gives you: \sum F=m \frac{v^2}{R} How big is it? By drawing a FBD on the bucket, the weight of the bucket (M*g) is equal to the tension in the rope for when \sum...
50. ### Uniform circular motion and angular momentum?

Homework Statement A sphere on top of a table is attached to a rope which goes through a hole in the table and is attached to a bucket at the other end. The sphere moves in a uniform circular motion with radius R. Water is then added to the bucket and the radius for the sphere's circular...