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  1. Y

    Conservation of Energy on Current-Carrying Wire in Magnetic Field

    So force on a current carrying wire = ILxB. If I have a bunch of bar magnets making a uniform magnetic field of strength B, then a 1 meter long wire of 0 ohms carrying 1 Amp, the force on that wire is (1)(1)xB = 1B. If I let that force move the wire for a time T, let's assume the wire moved a...
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    How does the saturation flux density affect magnetic field strength?

    So I'm confused what the Saturation Flux Density is referring to. Defintion says it is when you no longer get an increase in H-field when increasing external B-field. So, does the satuation flux mean the core can only create fields UP TO that saturation flux, or that it can make a stronger...
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    Understanding energy conservation in a solenoid

    Thanks, I got it now :)
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    Understanding energy conservation in a solenoid

    Ah sorry, I should have said the potential energy of the magnetic ball.
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    Understanding energy conservation in a solenoid

    So let's assume ideal wire, resistance = 0 Ohms. Also assume there is a magnetic ball 1 meter away and is attracted to the solenoid. If you have a loop of wire and run a small current through it, you get a magnetic field. This field attracts the magnetic ball, over a distance of 1 meter. If...
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    Not understanding work stored in a capacitor

    Ok, so dq represents the incremental charge to be applied on the capacitor plate and not an imaginary test charge between the plates? I'm getting my original info from here, first paragraph: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capeng2.html
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    Not understanding work stored in a capacitor

    Yes, that's where I am getting caught up. For a spring, each small distance you move affects the spring force, and that force is applied specifically for that small distance dx. But for a capacitor, each small charge you add to the plate increases the voltage, but why is that voltage applied...
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    Not understanding work stored in a capacitor

    I know V = q/c and W = Vq and dW = V dq. But why is Work in charging a capacitor W = integral of q/c dq? q seems to represent a charge on the capacitor plate and dq seems to represent a separate test charge. If I add a charge to the capacitor plate, I take take the resulting votage and multiply...
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    Why do sound waves not bounce off of each other?

    The reflection would be a wave bouncing off an incoming wave. S predicts you can add the two waves together to get the net wave, and that waves pass through each other. For two different amplitudes, my R hypothesis says the colliding waves will reflect with their original amplitudes, while S...
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    Why do sound waves not bounce off of each other?

    Yes, this is exactly the mentality that I had when asking this question. Unfortunately, Orodruin's answer went a bit over my head. So here's my thought experiment. We have a sound source producing a soundwave every second (1 Hz), the soundwave travels at 1 m/s, and there is a perfectly...
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    Where does static friction come from in ABS?

    Ok, so a perfectly slippery road and the car was in motion beforehand. Makes sense so far then.
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    Where does static friction come from in ABS?

    Oh, I was referring to a different scenario in that question, sorry. How could the car ever stop in a no-loss situation?
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    Where does static friction come from in ABS?

    It all makes sense except for how the car translates without tangential force.
  14. Y

    Where does static friction come from in ABS?

    Like a wheel spinning on ice just spins in place until it has grip to move forward (translation), which is offered by the tangential force from the road when the wheel pushes the ground.
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    Where does static friction come from in ABS?

    Can you show me when when I described a car at rest? Let me look at it from a sliding standpoint to see if it's easier for me. A car is sliding left with locked wheels. Kinetic friction by the road pushes to the right. This kinetic friction does two things: tries to spin the wheel CCW and...
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    Where does static friction come from in ABS?

    I am. Isn't that what we said in #37?
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    Where does static friction come from in ABS?

    I know the other torque is CW from the brakes, I just didn't mention it. But we also said before the brake torque and road torque to the right counteract each other, so no net torque is applied on the wheels. The rightward force on the bottom of the wheel keeps it spinning CCW, and a CCW...
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    Where does static friction come from in ABS?

    It will be CCW. But didn't you agree the CCW torque spins the wheel CCW? And also provides a rightward translation force in #41? So CCW wheel keeps the car moving left... but then I assume there's a split between how much force goes to rightward translation force and how much keeps the wheel...
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    Where does static friction come from in ABS?

    Not sure what you're asking. If the bottom of the wheel is to go left, then the wheel turns CW. If the car is to go left, then the wheel is to go CCW, and CCW is the direction of the torque from the road on the wheel, keeping the wheel spinning. Are you saying then the patch is wanting to move...
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    Where does static friction come from in ABS?

    So the translation force works to keep the wheels spinning which keeps the car going left, but also slows down the car? How does that work? And if forces come in pairs, what's the other force that makes the road want to push rightwards?
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    Where does static friction come from in ABS?

    In the context that the road provides translation force, then to stop the car going leftwards, the road has to provide a translation force to the right. But wouldn't this translation force also act as CCW torque on the wheels?
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    Where does static friction come from in ABS?

    I only typed what I did in post #6 in the context that no-slip MUST be observed. If the brakes apply CW torque, the wheel slows. If the whole car and wheel are translating at the same velocoty as it was before, then there will be slip due to the slowing of the wheels. If the no-slip has to...
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    Where does static friction come from in ABS?

    Right, the wheel will spin, but it will not translate until it has grip. So the road provides the translation force, I think.
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    Where does static friction come from in ABS?

    Isn't that how a wheel rolls? A CCW spinning wheel travels to the left because the bottom of the wheel travels rightwards, and the wheel pushes the road with a rightward force. So the road pushes on the wheel with a leftwards force. Also, is this correct: A rolling wheel with no slip...
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    Where does static friction come from in ABS?

    Wouldn't the CW torques oppose the CCW motion of the wheel? I don't see how it would accelerate. If I have a rolling wheel with no brakes, then the road is what slows down the wheel, right? If add brakes, then both the brakes and road will slow the wheel.
  26. Y

    Where does static friction come from in ABS?

    Sorry, still confused. Is there a difference between a wheel and a tire? *edit* Oh there is. Sorry, not really a car guy.
  27. Y

    Where does static friction come from in ABS?

    Ok, I think I might have confused the instantenous V = 0m/s on the bottom of the tire to mean a non-rotating tire. So yes, the tire is rotating. Brakes apply CW torque, and the road does as well. The interaction between the road and tire is static friction?
  28. Y

    Where does static friction come from in ABS?

    I'll try to identify both cases just so we're onthe same page. Case 1: The road applies kinetic friction rightwards on the bottom of the wheel, which acts as torque CCW on the wheel. The brakes applies a static friction against the wheel CW, and the wheel remains locked. Case 2: The rolling...
  29. Y

    Where does static friction come from in ABS?

    With a non-locked tire, the tire is slowed down by the internal axles by kinetic friction, the applied brakes by kinetic friction, and the road pushing leftwards on the bottom of the CCW spining wheel. The bolded part is my confusion. The contact patch is in the regime of static friction now...
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