Recent content by buksesele

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    Rotating cylinder - number of revolutions before it reach 2500 rpm

    Homework Statement A flywheel has shape as a homogeneous cylinder with mass m = 40,0 kg and radius r = 0,50 meters. The cylinder is rotating round the axis of symmetry, and is runned by a motor with constant angular velocity (w0). When the motor is switched off, the cylinder is affected by a...
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    Rotating cylinder, how long will it take before the angular velocity is halved

    Homework Statement A flywheel has shape as a homogeneous cylinder with mass m = 40,0 kg and radius r = 0,50 meters. The cylinder is rotating round the axis of symmetry, and is runned by a motor with constant angular velocity (w0). When the motor is switched off, the cylinder is affected by a...
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    Free-fall from space to earth surface

    Once again, thanks for all your help. We couldn't do it without you guys. Thanks for your reply Dick, we used Maple to calculate the time and we got 3217 seconds half way and 4223 seconds to hit the surface of Earth. Here are ours solution as promised, we post screenshots from Maple so you...
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    Free-fall from space to earth surface

    Hi We got it finally working now, big thanks to everybody that have helped us, especially you Patrick/nrqed. We wasted a lot of hours with d^2*r/dt^2 We will post the enitre solution (even though it's almost here already) tomorrow in case somebody else on the forum might have use for it...
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    Free-fall from space to earth surface

    Hi, thank you for your help Remember that the accelration isn't constant. We are having trouble finding v(t), this is how we have tried: F = m * a F = m * dv/dt Conversation of Energy: F = m*g + 1/2*m*v^2 Then we set: m*dv/dt = m*g + 1/2*m*v^2 Divide by m on both sides, and we get: dv/dt =...
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    Free-fall from space to earth surface

    1. The problem statement A object is dropped into a free-fall from a distance of 3 earthradiuses from the center of the earth. Starting at a velocity of 0. How long time does it take for the object to travel the halv distance to Earth (that would be the length of one EarthRadius), and how long...
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