# Rotating ring supported at a point

• nns91
In summary, the conversation discusses a problem involving a ring pivoted at one point and its maximum angular velocity when released from rest. The formula V=rw is mentioned, along with the need to consider moment of inertia and rotational kinetic energy. The parallel axis theorem is suggested to find the moment of inertia. In part b, the question asks for the initial angular velocity needed for the ring to make a complete revolution. The solution involves calculating potential energy and adding enough initial ω to make it past the top.
nns91

## Homework Statement

1. A ring 1.5 m in diameter is pivoted at one point on its circumference so that it is free to rotate about a horizontal axis. Initially, the line joining the support and center is horizontal.

a. If released from rest, what is its maximum angular velocity.

b. What must its initial angular velocity b if it is to jst make a complete revolution ?

V=rw

## The Attempt at a Solution

I don't know how to treat the ring as. Should I treat it as a hoop ?

How should I calculate maximum velocity ? I don't know what formula to use.

Any hint on what equation I should start on ??

Rotation suggests that you should be concerned about the moment of inertia and rotational kinetic energy sounds like to me.

In this case your moment is displaced, but I'm sure you can figure it out with the parallel axis theorem.

Yeah, I can definitely find I.

KE=(1/2)I*w^2 so I am still missing KE to solve for W right ?

So I got part a.

In part b. I use kinetic energy. I need to solve for v initial and I can calculate gravitational potential energy. However, the velocity at the top is not 0 so how can solve this ?

b. What must its initial angular velocity b if it is to jst make a complete revolution ?
How much more initial ω needs to be added to make it past the top when it gets there.

(Hint: How much more potential energy will it have to have stored when it gets to the top?)

## 1. What is a rotating ring supported at a point?

A rotating ring supported at a point is a physical system in which a ring or hoop is able to rotate around a fixed point or axis. This type of system is often used in engineering and physics experiments to demonstrate principles of rotation and angular momentum.

## 2. How does a rotating ring supported at a point work?

A rotating ring supported at a point works by having a pivot or support point that allows the ring to rotate freely around it. The ring may be attached to a motor or other source of rotation, or it may be manually rotated. The support point provides a fixed axis around which the ring can rotate.

## 3. What are the applications of a rotating ring supported at a point?

Rotating rings supported at a point have various applications in engineering, physics, and other fields. They are often used in experiments and demonstrations to study principles of rotation and angular momentum. They can also be used in mechanical systems, such as in machinery or vehicles, to transfer rotational energy or create motion.

## 4. What factors affect the rotation of a rotating ring supported at a point?

The rotation of a rotating ring supported at a point can be affected by several factors. These include the mass and shape of the ring, the speed and direction of rotation, the strength and stability of the support point, and any external forces or constraints acting on the system.

## 5. What are the advantages of using a rotating ring supported at a point in experiments?

A rotating ring supported at a point has several advantages for use in experiments. It allows for easy manipulation and control of rotational motion, and can be used to demonstrate principles of physics and engineering in a hands-on way. It also allows for precise measurements and calculations of rotation and angular momentum. Additionally, the simplicity and versatility of the system make it a useful tool in many different experiments and demonstrations.

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