A student places an object with a mass of m on a disk at a position r from the center of the disk. The student starts rotating the disk. When the disk reaches a speed of 0.8 m/s, the object starts to slide off the disk. What is the coefficient of static friction between the object and the disk? mass=100 g, r= 0.75 m

The coefficient of static friction between the object and the disk is 0.087.

Explanation:

According to the statement, the object on the disk experiments a centrifugal force due to static friction. From 2nd Newton's Law, we can represent the object by the following formula:

(1)

(2)

Where:

- Normal force from the ground on the object, measured in newtons.

- Mass of the object, measured in newtons.

- Gravitational acceleration, measured in meters per square second.

- Linear speed of rotation of the disk, measured in meters per second.

- Distance of the object from the center of the disk, measured in meters.

By applying (2) on (1), we obtain the following formula:

If we know that , and , then the coefficient of static friction between the object and the disk is:

The coefficient of static friction between the object and the disk is 0.087.

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