Recent content by OmegaFury

Homework Statement Find R_AB in the network. Look at attached file "Problem"Homework Equations R_S= R1+R2+R3+...Rn (for series resistors) 1/RP= 1/R1 + 1/R2 + 1/R3 + 1/Rn... (for parallel resistors) V=IR (ohm's law)The Attempt at a Solution Look at attached file "Problem Attempt" I know I'm...

Yes, I do. It's 2.9 x 10-7C

Well, it's not necessarily a mechanics question. I just thought a mechanics approach could solve the problem. The problem here is that I have to find the charge on the two spheres, even though I don't even know the electrical force between them. If Fg-Fe does not equal zero (Fg=Fe), as they...

I was wondering about that, direction-wise. The electrical force is only affecting the x-direction... If there is a missing force, I do not know of what it may be.

Alright. So. I can't use the equation Fg=Gm1m2/r2 since I do not know the position of the spheres relative to the earth. So I set up a coordinate system, of which the origin is in the middle where the two threads meet. Gravity only affects the y-direction, so the x-components are irrelevant. I...

Homework Statement Two small spheres, each with mass m = 5.0 g and charge q, are suspended from a point by threads of length L = 0.30 m. What is the charge on each sphere if the threads make an angle θ = 20° with the vertical? Homework Equations F=k|q1q2|/r2 The Attempt at a Solution I found...

Lol. Very true. Frustration is well-remembered while ease is a fleeting memory.

120V-20V= 100V That took me forever X__X

Okay. So. You meant find the voltage in the motor. I suppose that would be V=IR=4A x 5Ω=20V. Umm... E= Vline-Vmotor

The current would be 120V/5Ω= 24A ...E= -V?

I don't follow. I honestly don't fully understand what peak values are. Or rms values for that matter. They just come up in formulas for average power... All I know is that it has something to do with an alternating current, and they arise from moving electrical charges that periodically switch...

Does that mean that the back emf is equal to the line voltage minus the peak emf?

Homework Statement The resistance of the armature windings of a DC motor is 5Ω. The motor is connected to a 120V line. When the motor is spinning at full speed, it draws a current of 4A. The back EMF at full speed is: Homework Equations Pav=\frac{1}{2}I2peakR Pav=\frac{1}{2}εpeakIpeak...

Thanks for the help :smile:

Okay, so I use Pav=εrmsIrms Pav/εrms=800W/120V=6.67A. The rms current of the heater would be 16.7A-6.67A= 10.03A. Thus, the power rating of the heater would be 120V x 10.03A= 1203.6W. Is that correct?