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# Simple Harmonic Motion......... watch

1. Hi,

I have been studying this diagram:

There are some things that don't quite add up to me though. From the diagram you can see that the equation for the displacement x is:

x = Xcos(theta)

When the dot is to the far right theta is zero so x is equal to X and you get maximum displacement which I am fine with.

However, when the ball is above the center the displacement is zero but theta as it is given in the diagram doesn't make this work. When the ball is directly overhead there is no triangle you can draw so theta is zero again but this can't be the case as we know the displacement is zero at that point? So if theta was zero here it would imply that the displacement is maximum in the middle.
2. (Original post by Bibloski)
Hi,

I have been studying this diagram:

There are some things that don't quite add up to me though. From the diagram you can see that the equation for the displacement x is:

x = Xcos(theta)

When the dot is to the far right theta is zero so x is equal to X and you get maximum displacement which I am fine with.

However, when the ball is above the center the displacement is zero but theta as it is given in the diagram doesn't make this work. When the ball is directly overhead there is no triangle you can draw so theta is zero again but this can't be the case as we know the displacement is zero at that point? So if theta was zero here it would imply that the displacement is maximum in the middle.
When the object is overhead the angle
Just think of being equal to
3. (Original post by EricPiphany)
When the object is overhead the angle
Just think of being equal to
Oh I see so it's not in terms of the triangle just the angle between those points.

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Updated: November 9, 2015
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