How Does a Coin Roll in a Circle Without Falling?

In summary, the conversation discusses the concept of a coin rolling in a circle on a table due to the tilt of its axis. The question is raised about the forces involved and how the coin maintains its circular motion. Friction is identified as the mechanism for the change in direction once the coin starts to tilt.
  • #1
Sam_Goldberg
46
1
Hi guys, I have an extremely simple conceptual question. According to my textbook (in a problem), "if you start a coin rolling on a table with care, you can make it roll in a circle... the coin leans inward, with its axis tilted." I ask: how is this possible? The center of mass of the coin undergoes circular motion, yet the only forces that will ever be on the coin is the weight and normal force, which can never point in the centripetal direction. Thus, where am I going wrong?
 
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  • #2
Never mind, there has to be friction pointing inward. I got it.
 
  • #3
Allow me to continue the question.
Why does it go in circles, and not fall (by tilting) while the CM's trajectory is linear
and in the the original direction?

in other words, what's the mechanism that makes the coin change it's direction or turn once it started tilting?

thanks
 

What is "Coin Rolling in a Circle"?

"Coin Rolling in a Circle" is a scientific phenomenon where a coin is rolled in a circular motion on a flat surface, creating a unique pattern of movement and sound. It is often studied as an example of rotational motion and energy transfer.

What factors affect the trajectory and speed of a coin rolling in a circle?

The trajectory and speed of a coin rolling in a circle can be affected by various factors such as the initial velocity, the mass and shape of the coin, the surface friction, and the radius and angle of the circular path.

How is the energy transferred in a coin rolling in a circle?

As the coin rolls in a circular motion, kinetic energy is transferred from the coin's linear motion into rotational motion, causing the coin to spin. The energy is then transferred back into linear motion as the coin moves along the circular path.

What is the difference between a coin rolling in a circle and a coin sliding in a straight line?

The main difference between a coin rolling in a circle and a coin sliding in a straight line is the type of motion. A coin rolling in a circle has both linear and rotational motion, while a coin sliding in a straight line only has linear motion.

Why is "Coin Rolling in a Circle" used as an example in physics lessons?

"Coin Rolling in a Circle" is used as an example in physics lessons because it demonstrates several concepts such as rotational motion, energy transfer, and the relationship between linear and circular motion. It also provides a fun and relatable way to understand these complex concepts.

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