# Friction involving cylinder

1. May 5, 2010

### drewdiddy

1. The problem statement, all variables and given/known data

see attachment

2. Relevant equations

see attachment

3. The attempt at a solution

I understand everything about the problem except how to determine the angle P makes with the new horizontal axis (parallel with F)--see diagram under primary one... so that I can sum the forces up and answer the problem. My geometry is somewhat rusty and I'm not exactly sure what geometric property makes the angle 45. Any help is appreciated.

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2. May 5, 2010

### RTW69

Your solution looks correct to me. You summed the moments at B to get P=812 nt. You resolved the Ff and N into components in the x and y direction (all the angles look to be 45 degrees). You summed the forces in the in the x and y direction =0 and solved for mu.

3. May 22, 2010

### kleyb08

HELP me on this problem please it involves a cylinder and i cant figure out the correct solution.
(see attachment)

Here is the question:

Determine magnitude of force P that will cause the cylinder rotates.

Weight of Cylinder = 400N
Coefficient of friction in all surfaces is = 0.2

#### Attached Files:

• ###### physix.JPG
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4. May 22, 2010

### RTW69

I would draw a free body diagram of the cylinder. There will be normal and frictional forces on the A and B surfaces. Resolve P into X & Y directions. One of the things you will need to convince yourself of, by geometry, is if a line segment drawn from the origin (where A & B meet) through the center of the circle and connecting to P is a 90 degree angle. If it does you can take the moment about the origin and get rid of some of the ugliness relating to the frictional forces. Summing forces in the X & Y directions plus the moment equation should give you enough equations to solve the problem.

5. May 23, 2010