Pendulum question please help (1 Viewer)

Elise8842

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Could anyone show me how to do part c? Thanks a lot~ :)


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Elise8842

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That's what I've done so far... I assumed T1>T2 (not sure if that's correct though, can't think of other inequality ) , but the result is still ...wrong


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dunjaaa

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For part (c), you have to find the condition for the circular motion to exist. We set T2 > 0 and solve because T1 is always > 0 since r, w, g and m > 0 and also since 0 < θ < 90 (i.e. acute angle) -> implying sinθ and cosθ > 0. As for (d), think about when P is fixed (Hint: Consider the tensions (T1 & T2))
 
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Elise8842

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For part (c), you have to find the condition for the circular motion to exist. We set T2 > 0 and solve because T1 is always > 0 since r, w, g and m > 0 and also since 0 < θ < 90 (i.e. acute angle) -> implying sinθ and cosθ > 0. As for (d), think about when P is fixed (Hint: Consider the tensions (T1 & T2))

Thanks dunjaaa, but why is T2>0 the condition for the circular motion to exist?


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dunjaaa

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Yeah, all strings must be taut (i.e. T>0). For (d), the tensions T1 and T2 must be equal for P to be fixed.
 
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