# A rock starts from rest and slides down a hill. Find average friction force and mass.

SEE ATTACHMENT #1 for a diagram showing parameters.

A rock starts from rest then slides distance L= 5 m down a concave hill to a point which is h= 3 m below starting point.

During the slide, Q= 111 joules of heat are generated, and the final speed is V= 4.8 m/sec.

PART a. Find the average friction force.

PART b. Find the mass of the rock.

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#### Solution Preview

PART a.

Step 1.

The first step in a solution is to make or observe a careful diagram of the event.

From ATTACHMENT #1, come the following observations:

A. The friction force depends on the angle of the slope, therefore ...

#### Solution Summary

In a step by step solution, the problem is explained and solved.

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