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  1. C

    Lenz's and Faraday's Law Induction. Help on resistor and switches

    Okay, I read my text and I'm guessing the answer might be as follow but I do not know why: a) Right to left b) no current c) left to right
  2. C

    Lenz's and Faraday's Law Induction. Help on resistor and switches

    Lenz's and Faraday's Law Induction. Help on resistor and switches! Homework Statement Find the direction of the current in the resistor shown below a) at the instant the switch is closed b) after the switch has been closed for several minutes and c) at the instant the switch is opened...
  3. C

    Magnetic interactions

    Homework Statement A magnet is hung by a string and then placed near a wire as shown. When the switch is closed, the magnet rotates such that the ends of the magnet move as indicated by the arrows. At the instant the switch is closed determine: a) the direction of the current through the wire...
  4. C

    Find the direction and magnitude of the net magnetic field

    There's no direction because the two direction from the two wires cancel out. One is going into the page and another one is going out of the page
  5. C

    Straight wired magnetism

    Homework Statement Two long parallel conductors carry currents I1 = 3.00A and I2 = 3.00 A, both directed into the page as shown below. Determine the magnitude and direction of the resultant magnetic field at P. Homework Equations B = uI/(2*3.14*r) u = 1.26*10^-6 T*m/A The Attempt at a...
  6. C

    Find the direction and magnitude of the net magnetic field

    Homework Statement The two wires shown below carry currents of 5.00 A in opposite directions and are separated by 10.0 cm. Find the direction and magnitude of the net magnetic field a) at a point midway between the wires b) at point P1, 10.0 cm to the right of the wire on the right, and c) at...
  7. C

    Electric potential question

    How can the electric field be constant? E = k*(q/r^2) As you can see, electric field is dependent on the distance on the point charge
  8. C

    Has the current through battery 1 changed?

    From your statement, it seems that voltage and current are directly related. Increasing the current increases the voltage by using the equation, V = IR. However, there is also this other equation P = IV. This equation shows you that current and voltage are inversely related. How can this be so?
  9. C

    Has the current through battery 1 changed?

    Homework Statement In this problem, box A and box B contain unknown combinations of light buls. Bulb 1 is identical to bulb 2. The batteries are ideal. 1. a) In the circuit A (see first attached pic) the voltage across bulb 1 and the voltage across box A are equal. What, if anything can...
  10. C

    Electric Potential Difference homework help

    C'mon, can someone answer my question please. I want to understand the problem rather than getting an answer. Any help will be appreciated.
  11. C

    How to determine the brightness of a light bulb

    In general, does more current/less resistence mean the brighter of the light bulb? How does voltage take into account in this case
  12. C

    Electric Potential Difference homework help

    I thought that as long as there is constant force, there is always constant acceleration, unless force is changing at some point...
  13. C

    Electric Potential Difference homework help

    It doesn't matter if you define force to be positive or negative. You can set the coordinate system whichever way you want. But if the direction of force and the displacement traveled are the same, then work is positive. In this case, force and distanced traveled are the same, I think. If I am...
  14. C

    Electrical fields question

    oh okay, i just got it from one of your replies ranger, thanks
  15. C

    Electrical fields question

    Sorry, but I am just not getting this. E = k (q/r^2). As you can see, E depends on the distance between the charges acting on it. I know you're definitely right because the book says so, but it really did not explain much into it.
  16. C

    Electrical fields question

    I thought electric field is always putting +1C of charge at the places on the points. Therefore, the closer it is to the positive side, the stronger the electric field, and the faster it would get repelled by the positive charge
  17. C

    Velocity Question?

    you mean why is it 25.5 instead of 25? I think that's clearly a mistake unless I'm not catching something
  18. C

    Electrical fields question

    Homework Statement Two very large sheets of charge are separated by a distance d. One sheet has a surface charge density +o and the other a surface charge density -o. A small region near the center of the sheets is shown. 1. Draw arrows on the diagram to indicate the direction of the electric...
  19. C

    Electric Potential Difference homework help

    I edited my question to make it look like a problem instead of a show case
  20. C

    Electric potential question

    Homework Statement A positive charge of magnitude qo is shown in the diagram below. Points B and C are a distance r away from the charge and point A is a distance 2r from it. 1. Would the absolute value of work done by an external agent in moving the same test charge from point B to C be...
  21. C

    Electric Potential Difference homework help

    Show case? What are you talking about. I put on the questions I have problems on and then I put the answers I thought to be correct. Although I don't expect any of them to be correct.
  22. C

    Electric Potential Difference homework help

    Homework Statement Two charged rods, each with net charge -Qo, are held in place as shown in the diagram below a) A small test charge -qo travels from point X toi point Y along the circular arc shown. i. Draw an arrow at each point (X and Y) to show the direction of the electric force on...
  23. C

    Difference between parallel and series

    THANK YOU SO MUCH. I've been sitting at home for a day to think about this problem. I LOVE THIS FORUM
  24. C

    Difference between parallel and series

    Okay, so let's say we have a two bulb parallel circuit, each of them has 5? (whatever the units may be). If I plug that into the equation, it's going to be: 1/5 + 1/5 = 2.5 So putting the bulbs in parallel is going to decrease the resistence? Can anyone verify if I did the calculations...
  25. C

    Difference between parallel and series

    Yeah, you're right. It seems like I have a problem of telling whether increasing bulbs in a parallel circuit would increase the resistence or not. I know that in a two bulb parallel, there is going to be more current going through the battery than the single bulb circuit. So there is going to be...
  26. C

    Difference between parallel and series

    Difference between parallel and series circuit Okay, I am really confused about parallel and series and their differences. I know how they are set up, but I do not know how their arrangements may change the circuit may result in a change in total resistence. From my lab, I know that connecting...
  27. C

    Electrical Force Problem

    Sorry, but I don't think this is right. In this chapter, we have not yet gone over electrical potential energy.
  28. C

    Electrical Force Problem

    Gocha, but I still did not use the 20cm part from the question. I did the way you suggested: For the x direction: 1*10^3N/C*q - T*sin 15 = 0 For the y direction: Tcos15 - 0.002kg*9.8N/kg = 0 Solution: T = 0.0203N q = 5.18*10^-6C I still have doubt about my answer. The problem...
  29. C

    Electrical Force Problem

    I put the tension in the x direction into the equation already. I do not think there is a need to worry about the y direction because the electric field is on the parallel direction and so net charge on the ball only exists on the x direction
  30. C

    Electrical Force Problem

    Homework Statement A small 2.00-g plastic ball is suspended by a 20.0-cm-long string in a uniform electric field, as shown in the below diagram. If the ball is in equilibrium when the string makes a 15.0 degree angle with the vertical as indicated, what is the net charge on the ball? If you...
  31. C

    Equipotential lines

    Okay, we are supposed to do a lab in class and compare it to the real results. However, for some reason, my lab result is very different from my theoretical value. The lab is like this: I put a sheet of conductive paper with the dipole electrodes, one positive and one negative, of course...
  32. C

    Ideal gas law + Newton's 2nd law problem

    P = 1.79 atm, x = 0.907m. Sounds much better. Thank you!
  33. C

    Ideal gas law + Newton's 2nd law problem

    When I did your method, I got this: (P_i + kx/A)(V_i + Ax) = nRT_f (1 + 2000x/0.01) + (5 + 0.01x) = 8.93 5 + 0.01x + 1000000x + 2000x^2 = 8.93 2000x^2 + 1000000 -3.9 = 0 x = (.1*10^6 +/- sqrt (1*10^12 + 31200)) / 4000 x = -500m, 3.9*10-6m For this equation, I also got too small of a...
  34. C

    Ideal gas law + Newton's 2nd law problem

    Hey denverdoc, I used your method and I got 1.79atm for the pressure and 8.95*10^-6m for x. I think the pressure is right but x is wrong, since the value is too little to be noticeable in a real life experiment. This is what I did: N = S PA = kx Just by looking at the question, I know we have...
  35. C

    Ideal gas law + Newton's 2nd law problem

    Sorry, but I'm really bad at this. I am still confused about how you get the new equation Pf = Pi + kx/A. If Pf*A = kx, then wouldn't Pf = kx/A? Or are you saying I put down the wrong equation.
  36. C

    Ideal gas law + Newton's 2nd law problem

    Hey, thanks pal. This really helped a lot. denverdoc, I completely understand your explanation. But Andrew, regarding your equation, I do not get how you derived this equation Pf = Pi + kx. If you can explain it to me, that would be great. Unit of pressure is in atm or N/m^2 and unit of kx is N...
  37. C

    Ideal gas law + Newton's 2nd law problem

    V = P*k*x? Where did you get that equation from? I haven't seen an equation like that? Is it a derived equation? If so, where and how did you derive it?
  38. C

    Ideal gas law + Newton's 2nd law problem

    Homework Statement A cylinder has its lid connected to a spring with k = 2000 N/m. The cylinder is filled with 5.00 L of gas witht he spring relaxed at a pressure of 1.00 atm and a temperature of 20.0C. (a) If the lid has a cross-sectional area of 0.0100 m2 and negligible mass, how high will...
  39. C

    Buoyancy calculation help

    C'mon I need the help~~
  40. C

    What does mass, volume and density of displaced water mean?

    wow, THANKS. I finally got what displaced water means. You just answered my question that I've been thinking for 2 hours!
  41. C

    What does mass, volume and density of displaced water mean?

    Homework Statement I was having a lecture of buoyancy and I am confused about the meaning of displaced water. I asked my classmates about it and they said it is essentially the volume of the object when you put the object into the water. So now the question comes. There are three objects...
  42. C

    Buoyancy calculation help

    oh, I see now, it took me a while to think about it until you told me to draw boxes. So just to verify if my thinking is correct. Although object A has a greater depth difference, the pressure exerted on the vertical surface is less than that of object B because it has a smaller surface area. On...
  43. C

    Buoyancy calculation help

    Homework Statement Two objects of the same mass and volume but different shape are suspended from strings in a tank of water as shown. Is there more tension force on the string by object A or B? Link to the picture can be found at http://students.washington.edu/cy1126/Buoyancy.JPG [Broken]...
  44. C

    A rotational motion problem

    Are you saying I did this right? Yeah, now you've said it, I think it is realistic... Wow, I thought I didn't get this chapter at all
  45. C

    A rotational motion problem

    Homework Statement A stuntman whose mass is 70 kg swings from the end of a 4.0-m-long rope along the arc of a vertical circle. Assuming he starts from rest when the rope is horizontal, find the tensions on the rope that are required to make him follow his circular path,(a) at the beginning of...
  46. C

    I have no idea how to start this help

    b)ohhh, I see what u mean by using the conservation of energy. So, it is mgh = 0.5mv^2 + mgh, 9.8 * 4 = 0.5 * v^2 + 9.8 * 1.5 v = 7m/s. Plugging in the equation F = ma, F = m * v^2 / r F = 70kg * 7^2 / 4 F = 857N So the...
  47. C

    I have no idea how to start this help

    Well the angle at 1.5m from the bottom of the circle would be arccos(2.5/4) = 0.89 rad --> pi/2 - 089 rad = 0.68 rad is the angle at that moment. Using the equation F = ma, you get F = m*V^2/r. However, I don't see how you can get velocity if you don't have time... Can someone help it out? I'm...
  48. C

    A momentum physics question

    okay, I think I kinda know what ur saying. I'll give it an another shot Ft = mvf 400N * 1.0s * 0.5 = 61.2 kg * vf vf = 3.26 m/s x = vit + 0.5at^2 x = 3.26 * 1s + 0.5*9.8*1^2 = 8.16 m Is what I am doing correct? I don't get what u said about "You might want to use the equation that...
  49. C

    A momentum physics question

    Alright, I think I'm getting this. So: w = mg 600N/9.8N/kg = 61.2Kg Ft = mvf - mvi Ft = -mvi (1.5s * 400N * .5) * 1.5s = -61.2kg * Vi (in this part, do you have to divide the force by two like I did since the area under the curve is roughly a right triangle?) Vi = -7.35 m/s Therefore...
  50. C

    A momentum physics question

    Hmm... I don't see what ur saying. How can u get Vi from the graph before 0 sec. Am I missing some concept here?
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