![]() ![]() As noted in 28.27 – Roll cylinders down incline, the moment of inertia for a cylinder of uniform mass distribution is (1/2) MR 2, and for a hoop it is MR 2. As discussed in 28.24 – Angular acceleration and 28.30 – Waggle rods with different moments of inertia, the moment of inertia, I, for an object is the sum of the products of all its mass points and the squares of their distances from the axis of rotation, or I = Σ mr 2. The first two wheels have, essentially, a uniform mass distribution, and the wheel on the right has most of its mass near the edge. The first one (on the left in the photograph) has a diameter of 2.5 inches (6.2 cm), and the other two have a diameter of 8.0 inches (20. You can invite interested students to come up after class to try spinning the wheels.Īll the wheels in this demonstration have a mass of 960 g. Seeing the difference in moments of inertia, but seeing how fast the wheels are spinning, and then how long each one takes to stop, gives a good sense of how an object’s moment of inertia affects its rotational dynamics. This demonstration is perhaps better for feeling rather than You twist the shaft of each one so that they all start at about the same rotational speed, the wheel with least moment of inertia stops rotating first, and the one with the greatest moment of inertia stops last. ![]() So that you can spin them by twisting the rods that run through their centers. P.s: I'm running iOS5, and I've tried using iRecovery, it wouldnt see my iphone.Three wheels of equal mass but different moments of inertia are mounted I have a PC, but if there's a way to do what I'm asking on a Mac I have one of those too, if anyone has any ideas it will be greatly appreciated. So my question is: Is there a way to fix this without restoring my iPhone. I know how to fix this by DFU recovery, and retore, I ask this because my last restore was way back in October, I know its better then nothing, but i want to make sure there's nothing else I can do before I lose some important stuff. The wheel spins for exactly 5 seconds, then stops for exactly 2 mnutes and starts all over again. The only time the logo appears is when i do a hard reset, but after 2 minutes the Apple logo disappears and the black screen with white spinning wheel appears. I've had this happen before but this time it's differant. So I was on my last 3, and Cydia made me reboot, and now my phone is stuck inn this continuous boot. But after every 2-3 apps i would need to resping my iPhone 3Gs. ![]() ![]() I updated a few of my Cydia apps, because they needed to be. ![]()
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