Recent content by Heart

:eek: OK, I got it, still cannot believe I could miss the keyword "vertical". Thanks and sorry for this. Please don't get mad at me. I'm going to sleep now at almost 8 A.M. :zzz:

I think I might get it now, I just didn't read the question carefully and miss the "vertical part".

F = IlB P = Fv = (v^2)(l^2)(B^2)/R I just don't see how could the mass be relevant to this problem. If it was a particle then may be I could use the mass to do something with the circular motion but this just doesn't make sense. Please help.

Hi, I really need help with this question. Here's the question: "The figure shows a U-shaped conducting rail that is oriented vertically in a horizontal magnetic field. The rail has no electric resistance and does not move. A slide wire with mass m and resistance R can slide up and down...

Anyone? What I don't get is I cannot treat it as a single loop solenoid? If not then what method should I use? Please help.

:confused: Here's the question: "What is the magnetic field at the center of the loop in the figure?" OK, the question is really simple and it looks easy. However, when I put in the answer, it's wrong. I tried different methods/formulas but still got the wrong answers. Anyone cares to...

Thanks, I do now. :)

Thanks for the tip. I got the answer now. It didn't make sense to me though on why it'd take longer to heat when there're less resistors.

I found P to be 30 J/s; V is given = 30 volt and total R was found to be 30 ohms. I thought I got it wrong cos of using 30 ohms so I tried using 20 ohms (resistance of the resistor in the water bath) instead of the resistance of the total systemk, but I still got it wrong. Any suggestions...

"In the circuit in the figure, a 20-ohm resistor sits inside 102 g of pure water that is surrounded by insulating Styrofoam." "If the water is initially at temperature 10.1 deg. celsius, how long will it take for its temperature to rise to 58.9 deg. celsius? Use as the heat capacity of...

From now on, after they read your comment, people might even be more reluctant to reply. Come on, they are doing this for free and what they got is this? It's not like you're paying them. Even a prof often says things you don't get in class and you pay them like what, $500 a semester, at...

I have encoutered another problem with MasteringPhysics just now. The display/format looks weird and different. I'm using the same computer, same settings; everything's the same. Now it's confusing and hard to read the text. Some weird fonts and images showed up. I don't know why profs are...

Daniel, I'm lost here. I still don't get what can I use sigma for exactly? Sigma is the electric charge/area. Only the length is given, how can I find the electric field from sigma then when I have no clue what the area is? Also, in the above reply, I see that you use rho in the equation...

Thanks Daniel and Doctor Al, Here are what I got, if you don't mind can you check them? for a) E_vector net = {q/[4 pi epsilon_0 (x^2 + (0.5s)^2)}cos(theta)*2 i_unit N/C, the j_unit components (vertical y axis) will cancel out, while the i_unit components will complement each other. (So...

Thanks for the reply, but if you don't mind, can you clarify a bit? I know what epsilon_0 is but not sigma. My class hasn't reached that part yet. If sigma is given 1.0*10^-6 C/m^2, it still doesn't make sense on how E = sigma/epsilon_0; I tried but the units don't work out right. BTW...