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# Displacement and Velocity SHM graphs question watch

1. Could someone possibly help me make sense of this please?

Part c

Why, on the mark scheme does it say that the velocity graph should be half the amplitude? we were simply taught that it was a cos wave the same amplitude as the displacement graph.However, in the revision guide it says something different :/

Can someone possibly shed some light on this?

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2. (Original post by Mutleybm1996)
..
The amplitude of the velocity is , where A is the amplitude of the displacement. You know that . Thus the amplitude of the velocity relies purely on the frequency of the oscillation. You aren't given a time scale, or information of the time period or frequency for the motion, thus you cannot determine the amplitude of the velocity. However, perhaps you are missing the fact the mark scheme says as long as you draw a cosine wave, with a constant amplitude you get the marks? Their diagram just happens to have half the amplitude.

Click the spoiler to see why the amplitude of the velocity is as such:

Spoiler:
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I assumed a simple model for the equation here, no phase etc...

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Updated: January 21, 2015
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