Why Do Circularly Moving Objects Flip?

  • Thread starter RorschachDK
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In summary, the centripetal force is the only force acting on the car that can cause it to flip over. However, there are other factors at play, such as the normal contact forces at the wheels and the centrifugal force in a rotating frame, that contribute to the overall torque and rotation of the car. Ultimately, it is the balance of these forces that determines whether or not the car will flip over in a circular motion.
  • #1
RorschachDK
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Greetings

Im trying to understand how a car, and other things for that matter, that moves in a circular motion is able to flip over? As far as I know the only force acting is the centriputal force acting on the tires and going inwards. Is it this force that can act as a moment around the cars center of mass causing it to flip? Is the straight line inertia of the car playing a role?

Best Regards
 
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  • #2
Is it this force that can act as a moment around the cars center of mass causing it to flip?
Yes. (Centripetal force)
Is the straight line inertia of the car playing a role?
Classical mechanics would look completely different without, so... yes?
 
  • #3
mfb said:
Yes. (Centripetal force)
Classical mechanics would look completely different without, so... yes?

Its just that the centriputal force is the only force i can "see" in my free body diagram. If the inertia plays a role in the moment around the center of mass then shouldn´t it be force?

Best regards
 
  • #4
RorschachDK said:
If the inertia plays a role in the moment around the center of mass then shouldn´t it be force?
No, and I can't see a reason why you would assume this. The car in the curve is accelerating (and rotating if it flips over), clearly the forces (and momenta) are not balanced. Gravity is another force acting on the car, of course, but it does not lead to a torque around the center of mass.

Still centripetal force without u.
 
  • #5
I just can´t see what forces..I know about the centriputal force, but what other forces (other than gravity) acts on the car?
 
  • #7
RorschachDK said:
Its just that the centriputal force is the only force i can "see" in my free body diagram.
It's not the only force. There are vertical forces at the wheels (normal contact forces), which are greater at the outer wheels. So in sum they create a torque that opposes the torque of the horizontal centripetal force (friction). The car flips over if the torque of the centripetal force is greater, than from the contact distribution.

RorschachDK said:
If the inertia plays a role in the moment around the center of mass then shouldn´t it be force?
There are types of analysis where inertia is modeled as a force:
- Quasi-static analysis
- Analysis in a non-inertial frame
 
  • #8
From the non-rotating frame of reference, the centripetal force is applied at the wheels of the car, because the wheels are what grips the ground. The centripetal force is inward, and it pulls the bottom of the car inward toward the center. This creates a torque which rotates the car and causes it to flip over.

From a rotating frame, there is a centrifugal force which pulls outward on every part of the car. On average, you can treat it as a force on the center of mass on the car, pulling outward. But the car is also attached to the ground at the wheels, so the centrifugal force creates a torque which flips the car over.
 

1. Why do objects appear to flip when they are moving in a circular path?

Objects appear to flip when they are moving in a circular path due to a phenomenon called the "persistence of vision". This refers to the fact that our brain retains an image for a short period of time even after it has disappeared. As a result, when an object is moving in a circular path, our brain combines the images of the object at different points along its path, creating the illusion of a continuous motion and a flip.

2. Does the size of the object or the speed of its movement affect the flipping effect?

Yes, both the size of the object and the speed of its movement can affect the flipping effect. Objects that are larger and move at a faster speed are more likely to create a noticeable flipping effect. This is because the brain has more images to combine and process in a shorter amount of time, making the flipping effect more apparent.

3. Is the flipping effect the same for all circular motions?

No, the flipping effect can vary depending on the type of circular motion. For example, the flipping effect is more pronounced in a horizontal circular motion (like a spinning top) compared to a vertical circular motion (like a Ferris wheel). This is because our brain is more accustomed to seeing horizontal motion in our daily lives, making the flipping effect more noticeable in this type of motion.

4. Can the flipping effect be influenced by external factors?

Yes, the flipping effect can be influenced by external factors such as lighting and background. A well-lit environment with a plain background can reduce the flipping effect as our brain has less distractions to process. On the other hand, a dimly lit environment with a complex background can enhance the flipping effect as our brain struggles to process the images of the moving object.

5. Is the flipping effect a real physical phenomenon or just an illusion?

The flipping effect is a real physical phenomenon caused by the persistence of vision and the brain's ability to combine and process images. However, the flipping itself is an illusion as the object is not actually changing its orientation, but rather our brain is perceiving it to do so. This phenomenon has been studied and explained by scientists in the field of visual perception.

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