# Kinetic friction on an incline problem

1. Nov 11, 2004

### -Justin-

Hey guys this question has been stumping me to death! Any help at all would be greatly appreciated.

A mountain climber has tied himself to a rock and has begun to lower himself down a cliff. The rope passes over a frictionless pulley. At time t=0, the rock and the mountain climber are not moving, the mountain climber drops 10 meters in 6.2 seconds. The mass of the climber is 70kg, and the mass of the rock is 500kg. The mountain climber is directly vertical and the rock is sitting at 15 degrees above the x-axis.
What is the mountain climber's acceleration while he drops? Assume it is a constant acceleration.
Find the coefficient of kinetic friction between the rock and the side of the mountain.

2. Nov 11, 2004

### Sirus

I don't really understand the problem. Is the cliff also inclined at 15 degrees above the x-axis (doubtful!)? Where is the pulley? Where is the rock? A diagram would be helpful.

3. Nov 11, 2004

### -Justin-

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Last edited: Nov 11, 2004
4. Nov 12, 2004

### Pandemonium

For the first question, since you're told to assume constant acceleration, the question becomes a simple kinematics question. At t = 0, u = 0. At t = 6.2s, s = 10m. Apply your kinematics equation.

With the first part, you can get the acceleration of the mountain climber. Then, you should next find out the force the rock exerts on the climber, and from there you can find out the coefficient of friction.