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1. The energy for a pendulum and masses is given by:
E = 1/2L 2θ˙ 2(m 1 + 4m 2) Lg(m 1 + 2m 2) cos θ + E0

With eo a constant. How do you use conservation of energy to find the equation of motion for theta?
2. (Original post by Harriettttttt1)
The energy for a pendulum and masses is given by:
E = 1/2L 2θ˙ 2(m 1 + 4m 2) Lg(m 1 + 2m 2) cos θ + E0
This is unreadable. Can you put it up in latex, or post a copy of the question, please?

With eo a constant. How do you use conservation of energy to find the equation of motion for theta?
In general, you differentiate it e.g. consider conservation of motion for a body falling under gravity; its energy, E, is constant:

Differentiate this w.r.t to get:

i.e. mass x acceleration = force

This can be generalised to any case where you have a conservative force acting (i.e. a force like gravity, not like friction).

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