A block and disk with equal masses are released from the same height on a 30° incline. The block slides down the ramp while the disk rolls. If they both reach the bottom at the same time, what must be the coefficient of kinetic (sliding) friction?(adsbygoogle = window.adsbygoogle || []).push({});

ANSWER: mk = (1/3)tanX = (1/3)tan(30°) = 0.192

my question is... how did they derive the equation:

mk = (1/3)tanX

all I got was 2/3 g sin X

[tex]\mu m g cos\theta=ma[/tex]

[tex]\mu m g cos\theta=m*\frac{2}{3} g sin\theta[/tex]

[tex]\mu=\frac{2}{3}tan \theta[/tex]

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# Homework Help: Coefficient of kinetic friction on ramp

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