• Support PF! Buy your school textbooks, materials and every day products via PF Here!

Force, tension, torque and angular acceleration problem

  • Thread starter kottur
  • Start date
56
0
1. Homework Statement

A large 16.0 kg roll of paper with radius R=18.0 cm rests against the wall and is held in place by a bracket attached to a rod through the center of the roll. The rod turns without friction in the bracket, and the moment of inertia of the paper and rod about the axis is 0.260 kg m^2. The other end of the bracket is attached by a frictionless hinge to the wall such that the bracket makes an angle of 30.0° with the wall. The weight of the bracket is negligible. The coefficient of kinetic friction between the paper and the wall is μ= 0.25. A constant vertical force F= 60.0 N is applied to the paper, and the paper unrolls.

YF-10-54.jpg


1. What is the magnitude of the force that the rod exerts on the paper as it unrolls?

2. What is the magnitude of the angular acceleration of the roll?

2. Homework Equations

[itex]\sum F_{x}=0[/itex]

[itex]\sum F_{y}=0[/itex]

[itex]a=\frac{\tau}{I}[/itex]

3. The Attempt at a Solution

[itex]\sum F_{y}=60N+W-\mu*F=0[/itex] where [itex]W=16kg*9.8m/s^{2}[/itex] and [itex]\sum F_{x}=Tcos(30)=0[/itex]

I'm also not sure in what direction the force vector should be pointing when it says "What is the magnitude of the force that the rod exerts on the paper as it unrolls". The paper is in all directions around the rod so I'm not sure how to look at this problem.
Please help, I'm really lost.
 

Want to reply to this thread?

"Force, tension, torque and angular acceleration problem" You must log in or register to reply here.

Related Threads for: Force, tension, torque and angular acceleration problem

  • Posted
Replies
7
Views
5K
Replies
1
Views
365
Replies
2
Views
2K
Replies
10
Views
970
Replies
15
Views
17K
  • Posted
Replies
5
Views
8K
Replies
6
Views
11K
Replies
1
Views
6K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top