# The Coefficient of Static Friction

Place a coin at one edge of a textbook and slowly lift the book. When the coin just starts to slip down the incline, measure the angle (theta). Find Ff = m*g*sin(theta) and N = m*g*cos(theta).

Do I need to know the mass of the coin(m), gravity(g), and the angle(theta) the flate surface makes with the table?

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#### Solution Preview

Denote the coefficient of static friction by u. Denote the mass of the coin by m. Denote the supporting force and the friction force by N, F respectively. We can set up the following ...

#### Solution Summary

Denote the coefficient of static friction by u. Denote the mass of the coin by m. Denote the supporting force and the friction force by N, F respectively.

F - mgsin(theta) = 0

F = Nu

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