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

Torque and Angular Acceleration for a Rigid Body Problem

  • Thread starter Yosty22
  • Start date
185
4
1. Homework Statement

A 12.0-kg box resting on a horizontal, frictionless surface is attached to a 5.00-kg weight by a thin, light wire that passes over a frictionless pulley. The pulley has the shape of a uniform solid disk of mass 2.00kg and diameter 0.500m. After the system is released, find (a) The tension in the wire on both sides of the pulley, (b)the acceleartion of the box, and (c)the horizontal and vertical components of the force that the axle exerts on the pulley.

2. Homework Equations

Torque=R (cross) F = I \alpha
Newton's Laws

3. The Attempt at a Solution

I started with free body diagrams and writing out equations. For mass 1, the 12 kg box on the table, the only forces acting in the x direction are T1. On the hanging mass, m2, the only forces are the weight of the hanging mass and T2. I tried to figure out the torque about the pulley, using τ=I \alpha. I=.5mr2 and \alpha = a/r, so Torque = .5mr2*(a/r). However, I don't really know what to do from there. I figure both of the tensions create a torque, but i'm not sure what I need to do from here.

Any help would be greatly appreciated
 

tiny-tim

Science Advisor
Homework Helper
25,790
247
Hi Yosty22! :smile:
I figure both of the tensions create a torque …
That's correct. :smile:

Find the torque from each tension …

their difference is the total torque that you've just found. :wink:
 
185
4
Oh, duh. Thanks a lot, tiny-tim. Much appreciated. :)
 

haruspex

Science Advisor
Homework Helper
Insights Author
Gold Member
2018 Award
31,520
4,631
Fwiw, there are a couple of important details missing from the problem statement:
- That the wire is horizontal from the 12kg block to the pulley.
- That the pulley is only frictionless in relation to its axle; in relation to the wire it has unlimited(?) friction.
 

Want to reply to this thread?

"Torque and Angular Acceleration for a Rigid Body Problem" You must log in or register to reply here.

Related Threads for: Torque and Angular Acceleration for a Rigid Body Problem

Replies
2
Views
1K
  • Posted
Replies
6
Views
1K
Replies
8
Views
3K
Replies
1
Views
2K
  • Posted
Replies
1
Views
3K
  • Posted
Replies
5
Views
542
  • Posted
Replies
3
Views
1K
  • Posted
Replies
21
Views
4K

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