# Excitation from unbalanced mass

1. Jan 12, 2016

### Godfather_bek

1. The problem statement, all variables and given/known data
A rigid body of mass M slides vertically inside a friction-less prismatic pair. It is linked to the fixed frame through the spring of stiffness k, and a viscous damper with coefficient c. Beside the body, a point mass m rotates with constant speed w(omega) on a circular trajectory of radius r.(mass M also includes the point mass m)

2. Relevant equations
I don't know how to be with point mass. How to related vertical displacements with rotational? Can anyone suggest something..?

3. The attempt at a solution

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2. Jan 13, 2016

### Nidum

Examples this type of problem are to be found in many text books .

If you want to solve the problem yourself start by visualising the problem . When the eccentric mass is going around what do you expect to see the whole mechanism doing ?

3. Jan 14, 2016

### Godfather_bek

It is like washing machines model. If there was no rotating small mass, it would be much easier. How I realized it, as Ψ=Ωt and if Ψ is equal to Π/2, then centrifugal force Fc = mΩ2/r directed to upward. And if Ψ is -Π/2 it is downward. But how to be with equation of motion?

4. Jan 14, 2016