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Equations of motion for a dual mass-spring-damper

  • #1

Homework Statement



We have been given the following mass-spring-damper diagram, and are asked to derive the equations of motion. The positions of the two masses are given as q1 and q2.

upload_2018-10-11_19-6-27.png


The Attempt at a Solution



I began by drawing free-body diagrams for each mass.

upload_2018-10-11_19-8-17.png


Then I set up the equations using F_net = mq'' = sum of the forces acting on the mass.

upload_2018-10-11_19-9-15.png


How does that look? I'm not very experienced at these, and I'm concerned that I've written some of the expressions incorrectly, and that I have some of the signs wrong as well. Thank you.
 

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Answers and Replies

  • #2
haruspex
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Think again about the extension of the rightmost spring, and the direction of the force from the rightmost damper.
 

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