Homework Help: Question regarding simple harmonic motion

1. Jan 22, 2005

Sanosuke Sagara

I have my solution and my doubt in the attachment that followed.

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2. Jan 22, 2005

Andrew Mason

Your solution is right. But the equation of motion might be easier to use if you chose the sin instead of cos:

$$y = 3sin(\pi t - \pi/2)$$

This is because at t = 0, the mass is at maximum negative amplitude ($\theta = -\pi/2$)

So:

$$d = y-y_0 = 3sin(\pi t - \pi/2) - 3sin(-\pi/2) = 3sin(\pi t - \pi/2) + 3$$

For 1), where t = 1 sec., d = 3 +3 = 6
For 2), where t = .75 sec,$d = 3sin(\pi/4) + 3 = 5.12$

AM