We're doing a lab on centripetal force where we swing a mass on a string over our heads. The string passes through a glass sleeve and has masses suspended at the bottom of the string like this...http://www.batesville.k12.in.us/Physics/PhyNet/Mechanics/Circular%20Motion/labs/cf_and_speed.htm" [Broken](adsbygoogle = window.adsbygoogle || []).push({});

Although the experiment is not the same.

We had to adjust the radius and mass and then calculate the frequency for each trial. We then had to graph the relation between Force centripetal and the mass, Fc and frequency squared and finally Fc vs Radius. We then have to come up with proportionality statements for each and then combine each statement into one proportionality statement that relates all three.

We have the first two...

1) As mass increases Fc increases

2) As frequency increases Fc increases

But we are stuck at the radius. Our data shows that at a constant frequency and mass, then as the radius increases, Fc also increases (which makes sense since a greater velocity would be required to maintain the frequency of a string with a greater radius). But various internet sources state that as the radius increases, the force decreases?? Is this just because they are not taking frequency into account? Which is it?

Finally what should the radius proportionality statement and the final proportionality statement look like? Bear in mind the equation Fc= 4pi(2)rf(2)

Thanks for any help,

Andrew

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# Homework Help: Lab on centripetal force

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