Kinetic friction on an incline problem

In summary, the question asks about a mountain climber and a rock tied together and being lowered down a cliff with a frictionless pulley. The climber drops 10 meters in 6.2 seconds and has a mass of 70kg, while the rock has a mass of 500kg and is at a 15 degree angle above the x-axis. The first question asks for the climber's acceleration, assuming it is constant, and the second question asks for the coefficient of kinetic friction between the rock and the mountain. A diagram is provided for clarification. To solve the first question, one can use a kinematics equation with the given information, and then find the force the rock exerts on the climber to determine the
  • #1
-Justin-
3
0
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.
 
Physics news on Phys.org
  • #2
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
here is a picture of the drawing.

click either one of the links
http://img.photobucket.com/albums/v201/b16eh2/cc93d412.jpg [Broken]
 

Attachments

  • DSCF3029 (WinCE).JPG
    DSCF3029 (WinCE).JPG
    4.5 KB · Views: 461
Last edited by a moderator:
  • #4
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.
 

1. What is kinetic friction?

Kinetic friction is the force that acts between two surfaces in contact that are in relative motion. It opposes the direction of motion and is caused by the microscopic irregularities in the surfaces.

2. How does kinetic friction affect objects on an incline?

Kinetic friction on an incline is dependent on the angle of the incline and the coefficient of kinetic friction between the two surfaces. The force of kinetic friction acts parallel to the incline and opposes the motion of the object.

3. How is the coefficient of kinetic friction calculated?

The coefficient of kinetic friction is calculated by dividing the force of kinetic friction by the normal force between the two surfaces. It is a unitless value and varies depending on the materials in contact.

4. Can kinetic friction be reduced?

Yes, kinetic friction can be reduced by using materials with lower coefficients of friction, adding a lubricant between the surfaces, or by reducing the normal force between the surfaces.

5. How is the net force calculated in a kinetic friction on an incline problem?

The net force in a kinetic friction on an incline problem is calculated by subtracting the force of kinetic friction from the component of the object's weight parallel to the incline. This will determine the acceleration or deceleration of the object on the incline.

Similar threads

  • Introductory Physics Homework Help
Replies
3
Views
3K
Replies
19
Views
3K
  • Introductory Physics Homework Help
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
2K
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
13
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
9K
  • Introductory Physics Homework Help
Replies
28
Views
5K
  • Introductory Physics Homework Help
Replies
3
Views
936
  • Introductory Physics Homework Help
Replies
2
Views
901
Back
Top