Coin on rotating disc. What forces?

[faidros]

1.
If two coins are placed on a rotating disc (constant speed), what forces act on the coins, at what direction and in what proportions?
(The coins aren't sliding)


Gravity is one, and the normal force is the one counteracting on that.
But what forces could be expected in a horizontal plane?

A centripetalforce is crucial for the coins to obtain a uniform circular motion, and this is obviously pointing to the centre at all times.
I'm guessing the centripetal force through friction between the coin and the disc.. But is there another friction force that makes it possible for the coins to spin along with the disc?

Thanks for any help or comments.

 

[Doc Al]

I'm guessing the centripetal force through friction between the coin and the disc..

That's right--friction provides the centripetal force.

But is there another friction force that makes it possible for the coins to spin along with the disc?

Sounds like you think some tangential force is required. Not so. The motion is uniform circular motion, so the only acceleration is centripetal.

 

[m2003]

I can provide some insights on the forces acting on the coins on a rotating disc. Firstly, gravity is still acting on the coins since they are not in free fall and are still on the surface of the disc. However, the normal force from the disc is balancing out the force of gravity, keeping the coins in place.

In a horizontal plane, the main force acting on the coins is the centripetal force. This force is responsible for keeping the coins moving in a circular path and is directed towards the center of the disc. This force is necessary for the coins to maintain a constant speed and not fly off the disc.

In terms of friction, there are two types of friction forces that may be present. The first is static friction, which is the force that prevents the coins from sliding off the disc. This friction force acts in the opposite direction of the motion of the coins, keeping them in place on the disc.

The second type of friction force is kinetic friction, which is the force that allows the coins to spin along with the disc. This force is present due to the interaction between the coins and the surface of the disc, allowing them to rotate together.

In summary, the forces acting on the coins on a rotating disc are gravity, normal force, centripetal force, and friction forces. These forces work together to keep the coins in place and maintain their circular motion on the disc. I hope this helps to clarify the forces at play in this scenario.