SHM Energy considerations pendulum Watch

RussianQuestion
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#1
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Hi everyone, this shows the energy changes in a pendulum when it is undergoing SHM. I don't understand why they are opting for EPE here. Surely the tension (and thus EPE) is greatest at the equilibrium point?
Also, what has happened to the gravitational potential energy of the mass? This doesn't seem to be considered at all.
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Sonicalireza
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Usually I think the string is assumed to be light and inelastic so EPE shouldn’t matter. I find it unusual how it seems to be talking about EPE and 1/2kx^2 rather than mgh (GPE),which the table would be right for if it was for GPE.

Also, the GPE is max at the highest points and is transferred into KE, which is then transferred back to GPE when the pendulum goes back up.

Hopefully this helps.
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Teenie2
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Figure 1 is about the pendulum. The writing below it is about a mass oscillating on a spring is this maybe causing a bit of confusion?
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In figure 1, the maximum potential energy is mgh where h is the difference in height between points x and y. When the pendulum is at x, its energy is all potential and equals mgh. At y, this has all converted to kinetic energy of 0.5mv2 where v is the velocity at y (and where v is at its maximum). At z it has all changed back to potential energy again.
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RussianQuestion
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Thank you both, yes, I realised that the image and the text below are talking about completely different things!
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