Suspended Ring - Masses Released - Find Condition for Ring to Move Up

[Chileboy]

I'm having trouble with this problem...

A ring (mass = M) is suspended by an ideal cord from the ceiling, two equal masses (mass = m) are released from the top of the ring and slide down, one on either side of the ring, without friction. The question is:
What condition must the masses meet in order for the ring to move up?

I'm having trouble imagining it, I can't see which force could make the ring go up.

I'd apreciate any help.

 

[spacetime]

Ring and masses

As far as I see it, as the masses reach the lower half of the ring, there is a normal reaction acting on them exerted by the ring. But that is in the upward direction.

But after they collide at the bottom, they ( if they are elastic ) start moving up again and in the process, the normal recation exerted by the ring is downwards, and on the ring by the masses is upwards. Probably that is what makes it go up.


spacetime
http://www.geocities.com/physics_all/index.html

 

[GSXR750]

Hi there,

I understand that this problem can be a bit difficult to visualize, but let's break it down step by step to understand the physics behind it.

Firstly, we need to understand that the ring is suspended from the ceiling by an ideal cord. This means that the cord has no mass and does not stretch, and therefore only exerts a tension force on the ring.

Next, we have two equal masses (m) that are released from the top of the ring. These masses will slide down the ring without any friction, which means that the only forces acting on them are their weight (mg) and the tension force from the cord.

Now, in order for the ring to move up, there must be a net force acting on it in the upward direction. This means that the tension force from the cord must be greater than the weight of the ring and the two masses combined. Mathematically, we can represent this as:

Tension force > Weight of ring + 2(mg)

Since the masses are equal, we can rewrite this as:

Tension force > Weight of ring + 2(mg) = Mg + 2(mg)

Simplifying further, we get:

Tension force > (M+2m)g

Therefore, the condition for the ring to move up is that the tension force from the cord must be greater than the weight of the ring and the two masses combined, which can be expressed as Tension force > (M+2m)g.

I hope this helps to clarify the problem for you. Remember, it's always important to break down the problem and consider all the forces acting on the objects involved. Keep practicing and you'll get the hang of it!