Static friction is my answer correct?

In summary, the question asks for the maximum weight that can be hung on a hanger's arm when attached to a pole with the help of two friction forces. The given information includes the static friction coefficient, the length of the arm, and the distance between the points of attachment. The solution requires using three equations and taking into account the symmetry of forces. Despite being described as challenging, the problem can be solved using basic static rules.
  • #1
Femme_physics
Gold Member
2,550
1

Homework Statement



What's the max weight, P, you can hang on the hanger's arm, when the hanger arm is attached to a pole with the help of two friction forces at point A and B.

http://img543.imageshack.us/img543/8466/maxwqeight.jpg [Broken]


Homework Equations



Static friction coeffecient = 0.2
L = 0.5 [m]
d = 0.1 [m]

The Attempt at a Solution



Attached here... I didn't use all the equations but I wrote them anyway
 

Attachments

  • equalll.jpg
    equalll.jpg
    22.8 KB · Views: 435
Last edited by a moderator:
Physics news on Phys.org
  • #2
Dory: Nice work. Your current answer is incorrect. Hint 1: By symmetry, Fsb = Fsa. Now you have three unknowns, and three equations. Hint 2: Fs does not necessarily equal mus*N. Try again.
 
  • #3
Thanks for replying, nvn! I was actually told by my lecturer yesterday that this question is actualy super hard since there is an angle between to two Na's and he's only going to teach it after kinematics...from some reason he decided to put it in the exercise book to "challenge us" but he never told us it's super hard and takes a lot of thought... I personally thought it seems easy and can be solved with basic static rules... but I guess I'm wrong?.
 
  • #4
Femme_physics: You are right; it is solved with statics.
 
  • #5
Ah...then peculiar why would he say it's so complicated when it's not. I'll try again later.

I like your usage of my new nickname, nvn :) though annoyingly longer, at least I don't sound like a Tolkien's dwarf.
 

1. What is static friction?

Static friction is a force that prevents an object from moving when it is at rest or not in motion. It occurs when the surfaces of two objects are in contact with each other and have a tendency to resist motion.

2. How is static friction different from kinetic friction?

Static friction is the force that keeps an object at rest, while kinetic friction is the force that opposes the motion of an object. Kinetic friction only occurs when an object is in motion, while static friction can occur even when an object is not moving.

3. What factors affect the magnitude of static friction?

The magnitude of static friction depends on the nature of the surfaces in contact, the normal force between the objects, and the roughness of the surfaces. It also depends on the angle of the incline or the weight of the object.

4. How is static friction calculated?

Static friction is calculated using the formula: Fs ≤ μsN, where Fs is the force of static friction, μs is the coefficient of static friction, and N is the normal force. The value of μs varies depending on the surfaces in contact.

5. Can static friction be greater than kinetic friction?

Yes, static friction can be greater than kinetic friction. This is because static friction is the maximum amount of force that can be applied to an object before it starts to move, while kinetic friction is the force that opposes the motion of an object that is already in motion. In most cases, the coefficient of kinetic friction is lower than the coefficient of static friction.

Similar threads

  • Introductory Physics Homework Help
Replies
14
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
3K
  • Introductory Physics Homework Help
Replies
28
Views
5K
  • Introductory Physics Homework Help
Replies
7
Views
3K
  • Introductory Physics Homework Help
Replies
7
Views
3K
  • Introductory Physics Homework Help
Replies
13
Views
782
  • Introductory Physics Homework Help
Replies
10
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
3K
  • Introductory Physics Homework Help
Replies
6
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
1K
Back
Top