A coin is placed 17.0 cm from the axis of a rotating turntable of variable speed. When the speed of the turntable is slowly increased, the coin remains fixed on the turntable until a rate of 26.0 rpm (revolutions per minute) is reached, at which point the coin slides off. What is the coefficient of static friction between the coin and the turntable?

Respuesta :

Answer: The coefficient of static friction between the coin and the turntable is 0.13.

Explanation:

As we know that,

   Centripetal force = static frictional force

   [tex]\frac{mv^{2}}{r} = F_{s}[/tex]

or,  [tex]\frac{mv^{2}}{r} = \mu_{s} \times m \times g[/tex]

     v = [tex]\sqrt{\mu_{s} \times r \times g}[/tex]

or,  [tex]\mu_{s} = \frac{v^{2}}{rg}[/tex] ......... (1)

Here, it is given that

       r = 17 cm,      [tex]\omega[/tex] = 26 rpm,    

and  v = [tex]r \omega[/tex] ..........(2)

Putting equation (2) in equation (1) we get the following.

[tex]\mu_{s} = \frac{r^{2}\omega^{2}}{rg}[/tex]

            = [tex]\frac{17 \times 10^{-2} \times (26 \times [\frac{2 \times \pi}{60}]^{2})}{9.8}[/tex]

            = 0.128

            = 0.13 (approx)

Thus, we can conclude that the coefficient of static friction between the coin and the turntable is 0.13.