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kuruman is offline
Aug18-09, 07:37 AM
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Vertical circular motion

Let's take it from the top.

KE = (1/2)mv2; PE = mgh

The total mechanical energy is constant, KE + PE = Constant

Therefore when the pendulum goes higher, two things happen PE increases because h increases and KE decreases to keep the sum KE + PE constant.

But if KE decreases, v must also decrease.

Now in terms of angular velocity ω, v = ω r.

Here, r is the length of the pendulum. This stays constant as the pendulum swings back and forth.

So ...

Looking at v = ω r, if v decreases and r stays the same, what happens to ω?