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    PIR Motion Sensor pinout

    Hi all, I am trying to connect a Parallax PIR motion sensor to a mini-usb cable. The PIR sensor has three pins: GND (negative), VCC (positive) and OUT. The USB cable has four connections: GND, VCC and the DATA (+ and -). I am able to power up the sensor and see a voltage spike when...
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    Period of a pendulum?

    I have this question: You are doing some spring cleaning and decide to clean out your house. You want to make a new window in your wall with which to see nature come to life, so you tie a heavy mass to a short string and attach the string to a beam in your ceiling so it can swing freely like...
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    Calculating line integrals

    Calculating line integrals.... Ok, the problem is: h(x,y) = 3x (x^2 + y^4)^1/2 i + 6y^3 (x^2 + y^4)^1/2 j; over the arc: y = -(1 - x^2)^1/2 from (-1,0) to (1,0). In my notes, I had written: if h is a gradient, then the INTEGRAL of g*dr over curve C depends only on the endpoints. Also, if...
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    Help finding an equation for the level curve

    Hey guys, I tried it out, but I just don't get it. I have to find the equation for the level curve f(x, y)=(x^2 + y^2)e^(xy); that contains the point P(1,0). By the way, e^(xy) is read e to the x times y, just in case. What I did, which looks wrong the whole way was: (x^2 + y^2)e^(xy)...
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    Help finding an equation for the level curve

    Hey guys, I tried it out, but I just don't get it. I have to find the equation for the level curve f(x, y)=(x^2 + y^2)e^(xy); that contains the point P(1,0). By the way, e^(xy) is read e to the x times y, just in case. What I did, which looks wrong the whole way was: (x^2 + y^2)e^(xy)...
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    Vectors and crossproducts

    I'm given three points in 3D space (vectors), P, Q, and R. So I have to find a vector that is perpendicular to the plane formed by these points. Anyone? Thanks. I really just need some hint(s) for this.
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