Hey, i'm having trouble finding the friction constant in the following question:(adsbygoogle = window.adsbygoogle || []).push({});

Lisa is sitting on a carousel 0.55m from the centre. The carousel rotates at 15laps/min and Lisa weighs 33kg.

a) what is Lisa's velocity?

b) Lisa moves away from her spot so that she is rotating 1.2m from the centre. What is the lowest friction constant that will keep her in place?

Now I calculated the velocity by setting v=s/t=2πr/T, where T = 60s/15laps=4

so v=0.864 m/s (I'd appreciate if someone could tell me if this is right..)

I'm trying to pick between 2 methods for finding the friction constant:

1) calculating the friction constant could be done by v=(μrg)^{1/2}

which gives μ=0.05.

2)But then F_{μ}=μmg, and since F_{μ}is also = ma, I could calculate the centripetal acceleration by having a=v^{2/r=0.62 m/s2 And then putting it into F=ma, giving Fμ=20.5N. Putting the force back into Fμ=μmg, giving μ=0.063. So which answer is right? I would really appreciate if someone could help me out!}

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# Homework Help: Friction constant

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