## 9 thoughts on “3.50”

Which part of the problem represents parts d), e) and f)?

Part d) is the uncoupled modal equations of motion and the transformation from modal to physical coordinates
Part e) obtain the modal - coordinate time response solutions
part f) obtain physical - coordinate time response solutions

Part d) is what you did at the end here (I think) with solving for theta1(t) and theta2(t). Thanks for your help.

1. tutorpaul says:

Part d) begins at about 11:38 and runs until 13:32 (the transformation from modal to physical is $A^\star Q = X$ which I present at 18:10)

Part e) 13:34-18:01

Part f) 18:01-end.

2. nray95 says:

When trying to find the modal mass matrix, what did you use as your values in your M matrix? I've tried multiple different possibilities and none have worked out for me or given me your answer.

Thanks!

1. tutorpaul says:

I used the matrix given at the top of the problem:

1. Nicholas Parker says:

How did you derive the M matrix when using the lengths? It doesn't seem to match up. For value a11, shouldn't it be (m1+m2)l2^2? So (0.5kg+0.25kg)(0.1m)^2?

1. Nicholas Parker says:

Sorry, (0.5kg+0.25kg)(1m)^2, I got it!

3. Taylor Glenn says:

Was that a cat in the background.. nice

1. tutorpaul says:

Yes, that would be Lucy (Miss Boo). She was instrumental in this work!