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Homework Statement
Rigid body with one spring.
Homework Equations
Torque equations ( M=I * "alpha")
The Attempt at a Solution
So I think I can solve this problem but there is only one thing I do not understand.
When I am writing my torque equation I would think that the weight of the bar and the cube would affect the torque
M = I * a + Mb * g *0.4 cos (theta) + Mw * g * 0.4 cos (theta)  k*0.4sin(theta) *0.4 cos(theta)
but apparently the equation should be
M = I*a k*0.4sin(theta)*0.4cos(theta)
why does the mg of both the objects not affect the torque, whenever I try to include them the differential equation becomes unsolveable
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