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A coin is placed 34 cm from the center of a horizontal turntable, initially at rest. The turntable then begins to rotate. When the speed of the coin is 120 cm/s (rotating at a constant rate), the coin just begins to slip. The acceleration of gravity is 980 cm/s 2 . What is the coefficient of static friction between the coin and the turntable?

Respuesta :

Answer:

0.43

Explanation:

At the time of slipping , centripetal force becomes equal to the limiting static friction whose value is μ R or μ mg

Centripetal force which makes it rotate is given by

m v² / r where v is velocity of rotation and r is radius of circular orbit

So at limiting equilibrium

m v² /r = μ mg

μ =[tex]\frac{v^2}{rg}[/tex]

μ = [tex]\frac{120\times120}{34\times980}[/tex]

= .43

The coefficient of static friction between the coin and the turntable is 0.43

If a coin is placed 34 cm from the center of a horizontal turntable, initially at rest, at the time of slippage, the centripetal force is always equal to the friction force. Mathematically;

[tex]F_c=F_f\\\frac{mv^2}{r} = \mu mg\\\frac{v^2}{r} = \mu g\\\mu = \frac{v^2}{gr}[/tex]

Given the following parameters

v = 120 cm/s

g =  980 cm/s²

r = 34 cm

Substitute the given parameters into the formula to have:

[tex]\mu = \frac{120^2}{34 \times 980}\\\mu = \frac{14400}{33,320}\\\mu = 0.43[/tex]

Hence the coefficient of static friction between the coin and the turntable is 0.43

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