# Centripetal Force

by Vesper89
Tags: centripetal, force
 Mentor P: 40,274 There are two equivalent expressions for centripetal force: $$F_c = m v^2/r$$ or $$F_c = m \omega^2 r$$ Since $v = \omega r$, the two expressions are equivalent. ($\omega$ is the angular speed; it equals the frequency times $2 \pi$.) Since you are holding the frequency constant while you vary the radius, your results will follow the 2nd equation. If you held the speed constant as you varied the radius, your results would be described by the first equation.
 P: 81 Really! We did this lab last week too. How cool! Anyways what we foun was that Fc is directly proportional to Radius to the power of n if both mass and frequency are kept constant. For the constant frequency you have to square the frequency and then plot a graphy of squared frequency and Fc. (it shouls pass throught the orgin since when frequency square is zero so is Fc). Using this graph determine 4 values of freq. sqr. for contant Fc. Then find radis required for contant frequency. Then plot a graph of Fc vs. radius and use the graph to find relationship, or use log eqn.
P: 81

## Centripetal Force

For the final proportianality satement combine all the above proportianality. ours lookes a bit like this:
Fc is proportional to (m to the power of 0.816)(R to the power of 1.07)(freq. to the power of 1.31)
The above is just:
mR(f(squared))
 P: 6 I think that helped. I have the equation Fc=4п²rf² (which is the same as Fc=mw²r). I think the main reason we were having difficulty was because our data isn't very accurate. Anyway, thanks.

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