Which Coin Flies Off First from a Speeding Turntable?

In summary, the conversation discusses two coins on a turntable that is steadily speeding up with a counterclockwise rotation. One coin is further away than the other. The question is which coin will fly off the turntable first. The discussion includes equations for centrifugal acceleration and velocity, and the conclusion is that the further coin (coin 2) will fly off first, contrary to the initial belief of the person speaking. They then realize their mistake and rearrange the equation to understand why coin 2 will indeed fly off first. They also express a desire for an easier way to think about the problem.
  • #1
alingy1
325
0
Two coins are on a turntable that steadily speeds up, starting from rest, with a ccw rotation. Which coin flies off the turntable first?

Coin 2 is further away than coin 1.


MY ATTEMPT:

I believe centrifugal acceleration is done by friction. So fs=us*m*g. Fc=mv^2/r.
Then, v=sqroot(us*g*r).
Suppose coin 2 is at radius 2(r1), (r1) being the distance from center of coin 1.
angular velocity 1= r1(sqroot(us*g))
angular velocity 2=2r1(sqroot(us*g))

So, I conclude that coin 1 must be thrown off first. HOWEVER, the answer manual says it is coin 2, which is an obvious answer for me too. But, I can't seem to be able to prove it.
 
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  • #2
Your expressions for angular velocity are not right.
Check again.
The velocity (v) is OK.
 
  • #3
Ok, I rearranged it. I now understand! v=wr indeed!
Is there any easier way to think about this problem?
 

Related to Which Coin Flies Off First from a Speeding Turntable?

1. What are centrifugal force coins?

Centrifugal force coins are coins that are designed to demonstrate the concept of centrifugal force, which is the outward force that is experienced by an object when it is rotating around a central point.

2. How do centrifugal force coins work?

Centrifugal force coins have a weighted center and a rim that is slightly curved upwards. When the coin is spun, the weighted center creates a force that pushes the rim outwards, causing the coin to stay in motion and resist any inward forces.

3. What is the purpose of using centrifugal force coins?

The purpose of using centrifugal force coins is to visually demonstrate the concept of centrifugal force and its effects on objects that are in motion. It can also be used to explain how objects stay in orbit around a central point.

4. How are centrifugal force coins used in science experiments?

Centrifugal force coins are often used in science experiments to demonstrate the effects of centrifugal force. They can be used to show how the force changes with different speeds and distances, and how it can be affected by the weight and shape of the spinning object.

5. Are centrifugal force coins used in any real-life applications?

Centrifugal force coins are not commonly used in real-life applications. However, the concept of centrifugal force is used in various industries, such as in the design of amusement park rides and the functioning of centrifuges in laboratories.

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