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buksesele
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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 moment of force that is caused by friction.
When the motor is being swiched off, the rotational frequency of the cylinder was 5000 rpm. How many revolutions does the cylinder make before it stops?
Homework Equations
The friction: M = -kw
w = omega
k = (1,2 * 10^2) Nm/s
w0 = 5000 rpm
The Attempt at a Solution
The moment of inertia: I = (m*r^2)/2 (cylinder)
M = -kw => 1) w = -(M/k)
w = 1/2*5000
alpha = w/T = (1/2*w0)/T
1) (1/2*w0) = -(M/k)
(1/2*w0) = -((I*alpha)/k)
Any help will be appreciated :)