Max ω of circular hoop rotating around a peg and oscillation

In summary, the conversation discusses a problem involving a ring rotating around a peg and the use of equations of motion to solve for the moment of inertia. The person has a general idea of using rotational energy equations and the parallel axis theorem, but is unsure if they are on the right track. They also mention being completely lost on solving for part B, but believe solving for part A first may be helpful.
  • #1
Phantoful
30
3

Homework Statement


nGpQKiT.png


Homework Equations


F=ma
τ = Iα = rF
v=rω, a=rα
L = Iω
Center of Mass/Moment of intertia equations

The Attempt at a Solution

[/B]
So right now I've tried to model the force acting on the ring as it goes around the peg, but I think centripetal force is involved and I'm not sure how to use that in my equations of motion. A general idea I have is that rotational velocity should be highest when the hoop's center is at it's lowest possible point.

Say the peg is the z-axis coming in/out of the page, the moment of inertia of the hoop should be in relation to that axis. By the parallel axis theorem and the fact that a ring's moment of inertia is usually MR2, it would be I = MR2 + MR2. From this should I be using rotational energy equations or am I far off/should do something else?

For B I am completely lost but I'm pretty sure I might need to solve A first for it.
 

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  • #2
Phantoful said:
A general idea I have
Good idea. Your intiuition is good, but: on the basis of what physics considerations ?
Phantoful said:
centripetal force is involved
On the mark again ! [edit] to avoid wrongfooting you: specifics for it may not be needed for the answer..)
Phantoful said:
am I far off/should do something else
and again ! SO: no and no. Just go ahead (and post if stuck...)

Phantoful said:
For B I am completely lost but I'm pretty sure I might need to solve A first for it.
My feeling this time is different: there is no need, but solving A first is a good strategy.
 
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1. What is the maximum angular velocity of a circular hoop rotating around a peg?

The maximum angular velocity of a circular hoop rotating around a peg depends on the radius of the hoop, the distance between the hoop and the peg, and the mass of the hoop. The formula for maximum angular velocity is ω = √(g/r + a/r), where g is the acceleration due to gravity, r is the radius of the hoop, and a is the distance between the hoop and the peg.

2. How does the mass of the hoop affect its maximum angular velocity?

The mass of the hoop does not have a direct effect on its maximum angular velocity. However, a heavier hoop may require more energy to rotate at the same angular velocity as a lighter hoop due to its inertia.

3. What happens to the maximum angular velocity if the distance between the hoop and the peg is increased?

If the distance between the hoop and the peg is increased, the maximum angular velocity will decrease. This is because the hoop has to travel a longer distance to complete one rotation, and thus requires more energy.

4. Can the maximum angular velocity be exceeded?

Yes, the maximum angular velocity can be exceeded if an external force is applied to the hoop. However, this can cause the hoop to lose its circular motion and potentially fly off the peg.

5. How does the shape of the hoop affect its maximum angular velocity?

The shape of the hoop does not have a significant effect on its maximum angular velocity. As long as the hoop is circular and has a consistent radius, the formula for maximum angular velocity will still apply.

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