# A coin placed on the cover of a book just begins to move when the cover makes an angle of 388 with the horizontal.?

What is the coefficient of static friction?

### 4 Answers

- AmyLv 72 years ago
An object placed on an incline begins to move when the component of gravity along the incline begins to exceed the maximum force static friction can exert.

As the angle increases:

* The component of gravity along the incline increases

* The force of static friction countering that component likewise increases, if it can.

* The component of gravity perpendicular to the incline decreases

* The normal force countering that component likewise decreases

* The coefficient of friction is constant

* The maximum force that static friction can exert decreases.

Calculate each of these force components, as multiples of mg, for the given angle.

Solve for μs.

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- Bob LLv 72 years ago
There is no angle of 388. Angles top out at 359 degrees 59 minutes.

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- 2 years ago
Image result for what is the coefficient of static frictionhyperphysics.phy-astr.gsu.edu

The force of static friction can be calculated by taking the coefficient of friction between the two surfaces and multiplying it by the normal force that the surface is applying to the object. On a flat surface, the normal force is equal to the force of gravity acting down on the object.

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