# Spring, Mass , Dumper system. Dumper Value.

1. May 17, 2010

### Bluesky1

Spring, Mass , Damper system. Damper Value.

1. The problem statement, all variables and given/known data

Hi,

I have a problem with first question from site below:

3. The attempt at a solution

I was trying to solve it using transmissibility equation but there is no mass so I cant find a natural frequency.

Transmissibility is in this case 0.01% because the isolation required is 99.9%.

T= sqrt {[1+4*d^2*(f/f0)^2]/[(1-(f/f0)^2)^2 + 4*d^2*(f/f0)^2]}

d- damper value
f- frequency which is 100Hz
f0- natural frequency

The other way is to use dynamic equation and then find transfer function:

dynamic equation: cx' + kx = M x''

but the Mass is unknown and it's the problem.

Last edited: May 17, 2010
2. May 18, 2010

### Gokul43201

Staff Emeritus
I believe you are correct - you need the mass, and there is no way to absorb it into the value of the damping coefficient. I guess you could proceed by assuming some convenient value for the mass.

3. May 19, 2010