# Lagrange equation for mass-spring-damper-pendulum

by tanquat
Tags: harmonics, lagrange, oscillations, spring-mass, vibrations
 P: 3 Can someone kind of give me a step by step as to how you get the equations of motion for this problem? the answer is this: Though im not quite sure what b and c are. i guess for reference here is what it looks like after transforming it some: Here is the website if you need to do any clarification: http://www.enm.bris.ac.uk/teaching/p...a9213/msp.html I have another problem similar to this for homework, i just wnat to see this one layed out before i work on my other. Thanks!
 P: 34 $$mv_{x} + MV_{x} = C1$$ $$\int(-BV_{y})dt + \int(-KY)dt + MV_{y} + mv_{y} = C2$$ $$v_{x} = V_{x} + lsin(\varphi)\frac{d\varphi}{dt}$$ $$v_{y} = V_{y} + lcos(\varphi)\frac{d\varphi}{dt}$$
 P: 3 um, could you clarify a little bit more? my main problem is understanding the relationship between the pendulum and the first mass, M
P: 34

## Lagrange equation for mass-spring-damper-pendulum

uppercase symbols for M, small symbols for m.
B is damping coefficient of damper attached on M and K is spring coefficient.
apply momentum conservation on both x and y direction can get above equatiions.
C1 and C2 are initial conditions.
derivation of second equation will be force-acceleration equation.
Not difficult to understant. just "Ft + MV + mv = a constant" in differential form.
It's a second order system. If you re-arrange them, you can get simillar equations as that on the webpage you provided.
If there's something missing, might be geometry equations.

Good Luck.
 P: 3 thanks i appreciate it. I just started a vibrations course and this problem is similar to what i have in homework. i tried looking tah the lagrange equations to get an idea on an answer so i can go back and do the system again using newtonian equations, though as of last night it has started making me rather frustrated :/ and honestly its the pendulum thats messing me up.

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