(adsbygoogle = window.adsbygoogle || []).push({}); HELP!!!Rotational kinetic energy problem

1. The problem statement, all variables and given/known data

A 4.00kg mass and a 3.00kg mass are attached to opposite ends of a thin 42.0cm long horizontal rod. the system is rotating at angular speed omega=5.60rad/s about a vertical axle at the center of the rod. determine a) kinetic energy K of the system, and b) the net force on each mass. c)repeat parts a and b assuming that the axle passes through the center mass of the system.

3. The attempt at a solution

a)KE=1/2mv^2

m=4.00kg+3.00kg=7.00kg

v=radius*omega=21*5.60=117.6

therefore KE=48404.16J

b)Net force=F_t-F_f=F_t-mu*F_n

i don't really know how to get mu from this problem. and how do I get acceleration for F_t

c)total mass*radius for center mass=m1r1+m2r2=4*21+3*21=147

7*radius of center mass=147

therefore radius of center mass=147/7=21...

But it is same as question a and b

Can anybody help me with it. Thank you very much.

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# Homework Help: HELP Rotational kinetic energy problem

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