- #1

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Could someone help me, please?

Thanks in advance!!

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- Thread starter MonsieurWise
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- #1

- 53

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Could someone help me, please?

Thanks in advance!!

- #2

rock.freak667

Homework Helper

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- #3

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If the earthquake produces mainly vertical displacements - and thus vertical accelerations - then I'm not sure how your pendulum would measure this.

Assuming you are measuring only the horizontal motion, then yes it makes sense that the maximum angular displacement would be related to the strength of the earthquake, but I think your teacher wants to to quantify this somehow. For example, if you measure that your pendulum has swung to 30 degrees from vertical, what does that indicate about the earthquake? The horizontal force exerted on the pendulum? The energy required to move it that far?

You need to be able to translate your angle to some quantity that relates directly to the strength of the earthquake.

You might consider a simpler version, namely a mass connected to a spring, such that it is able to move in a horizontal direction. Since it's a one-dimensional problem, it's a bit easier, and then once you have it solved you can then extend it to the case of a mass suspended by three perpendicular springs (in the x, y, and z directions) and thus measure displacements in all directions. This is the basic design of an accelerometer.

- #4

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I would say that the potential energy thing is the easiest thing for a 9th grader now...(he has 2 more days, he can't learn angular stuff that fast...I think). I say that the KE from the earthquake move the ball in the pendulum to a height (because it is hung by a string). Using the angle, I can calculate the vertical displacement of the ball, and this is how the angle related to the strength of the earthquake... Do you think this is enough...or is there any flaws in what I'm saying...?

My teacher is worrying that the judges will ask him about tangential and radial acceleration, but I think, at this point, (and at his level), the judges will not ask such a thing...

Thank you all again!

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