Torque and Forces in Spool Movement: Solving for Net Torque and Static Friction

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In summary, the conversation is about solving a multiple choice question involving forces and torque. The question involves finding the net torque and eliminating options using intuition about rolling and slipping. Upon further analysis and drawing a diagram, it is determined that the torque of tension is just Tr, not Trcostheta. Taking moments about the point of contact with the ground simplifies the problem.
  • #1
jaewonjung
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Homework Statement
Problem in picture
Relevant Equations
Fnet=ma
Forces in the x direction: static friction left=Tcostheta to the right
Forces in the y direction: W= Normal force + Tsintheta
Net torque: rTcostheta-RFs=0

Fs=Tcostheta,
rTcostheta-R(Tcostheta)=0
rTcostheta=RTcostheta
r=R

Please help
 

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  • #2
This is a multiple choice question, so try to use intuition about rolling vs slipping to eliminate answers. Look at each variable in turn: for instance what if r=R? Will it roll? Then think about theta...what if it is zero...90deg...
 
  • #3
jaewonjung said:
Net torque: rTcostheta-RFs=0
Looks like you are taking moments about the centre of the cylinder. Think again about the torque due to T. Maybe draw a nice big picture, carefully.
(There is a better choice of axis for this problem.)
 
  • #4
I solved it! The torque of the Tension is just Tr, not Trcostheta. Thanks for the help!
 
  • #5
jaewonjung said:
I solved it! The torque of the Tension is just Tr, not Trcostheta. Thanks for the help!
Good.
Note that if you take moments about the point of contact with the ground instead it becomes a matter of simple geometry.
 

Related to Torque and Forces in Spool Movement: Solving for Net Torque and Static Friction

1. What is "spool moving without rolling"?

Spool moving without rolling is a phenomenon where a spool or a cylindrical object moves from one point to another without rotating or rolling. This motion is achieved by creating an external force that causes the spool to slide or glide instead of rolling.

2. What are the applications of spool moving without rolling?

Spool moving without rolling has various applications in different fields such as manufacturing, robotics, and transportation. It can be used to move heavy objects, conveyor belts, and even vehicles without the need for wheels or tracks.

3. How is spool moving without rolling different from traditional rolling motion?

In traditional rolling motion, an object moves by rotating around its own axis while in spool moving without rolling, the object moves by sliding or gliding. This results in lower friction and allows for smoother and more controlled movement.

4. What are the advantages of spool moving without rolling?

One of the main advantages of spool moving without rolling is the reduction of friction, which results in less wear and tear on the object and its surroundings. This can also lead to increased efficiency and cost savings in industries where frequent movement of heavy objects is required. Additionally, this motion can also be used in environments where traditional rolling motion is not feasible, such as in space exploration.

5. What are the challenges in implementing spool moving without rolling?

One of the main challenges in implementing spool moving without rolling is creating the external force that will cause the object to slide or glide. This force needs to be carefully controlled to ensure smooth and precise movement. Additionally, the design of the spool and the surface it is moving on needs to be carefully considered to prevent any damage or instability.

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