Find the Coefficient of Friction Given Frequency

AI Thread Summary
To find the coefficient of friction for a rubber eraser on a cardboard turntable rotating at 33 1/3 RPM, the centripetal acceleration must be calculated using the formula ac = 4π²rf². The challenge arises from the lack of specific values for mass or radius, complicating the calculations. The relationship between friction and acceleration is expressed as μFn = m x ac, where μ represents the coefficient of friction. The discussion highlights the difficulty in isolating variables due to the unknown radius and mass. Understanding the properties of the materials involved may provide additional insights, but the problem remains unsolved without further information.
CoffexCream
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Homework Statement


A rubber Eraser is placed on a cardboard record on a turntable. The turntable is set to 33 1/3 rotations per minute. what is the max radius for the eraser to be placed without slipping. but first calculate the coefficient of friction. You will not be given mass or radius of the 'record'

Homework Equations


ac=V2/r
ac= 4pi2rf2
us=Tan \theta

The Attempt at a Solution


no idea as to how to get this...i can't seem to make any connections...

\muFn=m x ac
\mu=Tan \theta
Tan \theta=m x ac
Tan \theta= ac / g
Tan \theta= 4\pi^2rf^2
then acceleration can be either of the centripetal acceleration equations but the n i get totally stuck because i can't get rid of r xD
 
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perhaps the fact that it is a rubber eraser and a cardboard turntable means something. i would check your textbook for useful tables
 
unfortunately this question was randomly made by my teacher and its not in the textbook >.>
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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