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gibson:teaching:fall-2013:math445:lecture21

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gibson:teaching:fall-2013:math445:lecture21 [2013/12/03 05:48]
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gibson [Physics]
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 Pendulum physics, F = ma with linear air resistance Pendulum physics, F = ma with linear air resistance
  
-m l theta''​ = -mg sin theta - b theta' ​    +<​latex>​ 
 + m l \theta''​ = -mg sin \theta - b \theta' ​    
  
-theta''​ + c theta' + g/l sin theta = 0    ​+ \theta''​ + c \theta' + g/l \sin \theta = 0    ​ 
 +</​latex>​
  
 This is a 2nd-order nonlinear differential equation in one variable, theta. This is a 2nd-order nonlinear differential equation in one variable, theta.
-2nd order b/c theta''​ term. Nonlinear b/c sin theta. Linearization for small  +2nd order b/c $\theta''​term. Nonlinear b/c $\sin \theta$. Linearization for small  
-theta would approximate sin theta = theta for small theta. No big thing+theta would approximate sin theta = theta for small $\theta$. No big thing
  
 =====Get ODE into Matlab form===== =====Get ODE into Matlab form=====
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 to a 1st order ODE in n variables, as follows. Let to a 1st order ODE in n variables, as follows. Let
  
 +<​latex>​
   x1 = theta   x1 = theta
   x2 = theta'   x2 = theta'
 +</​latex>​
  
 Then Then
gibson/teaching/fall-2013/math445/lecture21.1386078488.txt.gz · Last modified: 2013/12/03 05:48 by gibson