Constraint forces on a circle

[usljoo]

Main Question or Discussion Point

when a particle is constraint to move on a circle, what are the constraint forces

 

[Studiot]

when a particle is constraint to move on a circle, what are the constraint forces

What is the particle?

What forces do you know that can act on particles?
Could any of these provide a 'central force'?

 

[HallsofIvy]

This depends upon HOW the particle is constrained to move in a circle. If the particle is attached to a circular track, the answer is obvious. If the particle is an electron going around a positive charge, the answer is also obvious but not the same as before.

Frankly, this looks like a question at the end of a chapter of a basic science text- where they are really testing whether you have read the chapter!

 

[tiny-tim]

when a particle is constraint to move on a circle, what are the constraint forces

usljoo, you know the procedure by now …

you tell us what you think the answer is,

and then we comment!

 

[usljoo]

ok look at the attachment

 

[tiny-tim]

my mac doesn't do .doc

how long can it be? can't you find the time to type it out for us?

 

[usljoo]

i hope ur mac does pdf :P

 

[tiny-tim]

i don't understand what your .pdf has to do with the question …

when a particle is constraint to move on a circle, what are the constraint forces

 

[Studiot]

Looking at your diagram I think I understand your question.

Unfortunately, taking your posts in this thread and your previous one, you seem to have a basic misunderstanding about circular motion.

And this is the reason why it is harder to apply a force like on the picture to a circle of smaller radius and that is because there will be a component of the centripetal force that is opposite to the applied force F on the picture and that’s why torque gets smaller with r.

There is no way that F has anything to do with motion around the circle you have drawn.

None of this is meant as a personal criticism; I really am trying to help.

You did not bother to answer my previous question. All my questions are designed to help and further understanding.

Have a look at this recent thread, where I like to think the OP went away with a better understanding and achieved something for himself.

https://www.physicsforums.com/showthread.php?t=468864

Now just answer this simple question.

If you take a string and pull it out taught so it is under tension, what are the forces acting in the string and on the string?
Can you draw a simple diagram?

 

[usljoo]

Looking at your diagram I think I understand your question.

Unfortunately, taking your posts in this thread and your previous one, you seem to have a basic misunderstanding about circular motion.



There is no way that F has anything to do with motion around the circle you have drawn.

None of this is meant as a personal criticism; I really am trying to help.

You did not bother to answer my previous question. All my questions are designed to help and further understanding.

Have a look at this recent thread, where I like to think the OP went away with a better understanding and achieved something for himself.

https://www.physicsforums.com/showthread.php?t=468864

Now just answer this simple question.

If you take a string and pull it out taught so it is under tension, what are the forces acting in the string and on the string?
Can you draw a simple diagram?

the forces on the string are the tension force witch acts on the pivot where you binded the string and the same acts also on your hand but i dont see what this has anything to do witch my question

im asking you under these constraints that i have drawn and when you apply a tangential force F as shown what are the forces of the constraint and how will they affect my force F

 

[Studiot]

the forces on the string are the tension force witch acts on the pivot

This doesn't make sense. Is the force acting on the string or the pivot? I actually asked about the string.

You really need to pay attention to what is said.

Did you draw a diagram?

And, yes, the question has direct relevance, which will become clear.

 

[usljoo]

well look man i really am no beginner here and the question is far from trivial so dont ask me these questions about the string because you didnt get my question i think better tell me what the forces of constraints are

 

[Studiot]

go well