Why is there "weightlessness" on the top of a verticle circle?

In summary, the concept of weightlessness in vertical circular motion is often confusing because the weight of an object is not actually cancelled out by an equal and opposite force. Instead, the necessary centripetal force to stay in the circular path is provided by the weight of the object itself. This results in a net weight of zero at the top of the circle. This can also be seen by comparing free body diagrams of an object on Earth and an object in vertical circular motion.
  • #1
1832vin
58
1
i'm ashamed, that i never understand this, eventhough I'm studying quantum mechanics...

so... why is there "weightlessness" on the top of a verticle circular motion?
ie, if a plane if flying in verticle circles, why is there weightlessness while on the top of a circular path?
i mean, if it's weightlessness, that means that the wieght of the object is canceled by a force equal and opposite, leaing to no net force, not change in interia, and therefore weightlessness...

however, that's not the case...? on the top of a circlar motion/path, the wieght points down to earth, whilst the centripital force is also pointing downwards... wouldn't that make the person to feel even more force applied downwards?

the answers always "the weight = centriplital force" but i don't get how does that mean "weightlessness"

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  • #2
In order to stay in the circle, you need a force directed towards the center of the circle and with magnitude [itex]C=m\cdot \frac{\omega^{2}}{R} [/itex]. At the top of the circle, you still need that force and the only force you have available is [itex]F=m\cdot g [/itex] which is pointed downwards. Therefore, the net "weight" at the top of the circle is [itex]F-C=m\cdot g-\frac{\omega^{2}}{R} [/itex]. From this formula you can see that [itex]F-C=0 [/itex] when [itex]m\cdot g-m\cdot \frac{\omega^{2}}{R}=0 [/itex].
 
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  • #3
In fact, if you are moving faster than the minimum speed to maintain the circular orbit, then your weight is pointing upwards when you're at the highest point.
 
  • #4
Why not draw a free body diagram for an object sitting on Earth and see how it differs from what you drew?
 

1. Why do objects feel weightless at the top of a vertical circle?

Objects feel weightless at the top of a vertical circle because the centripetal force acting on the object cancels out the force of gravity. This creates a state of apparent weightlessness, also known as zero-g, where the object is not experiencing any net force.

2. What is the role of centripetal force in creating weightlessness at the top of a vertical circle?

Centripetal force is the force that keeps an object moving in a circular path. In the case of a vertical circle, the centripetal force is directed towards the center of the circle and is responsible for keeping the object in motion. At the top of the circle, the centripetal force is equal in magnitude and opposite in direction to the force of gravity, resulting in weightlessness.

3. Does the speed of the object affect the feeling of weightlessness at the top of a vertical circle?

Yes, the speed of the object does affect the feeling of weightlessness at the top of a vertical circle. The higher the speed, the greater the centripetal force needed to keep the object in motion, and therefore the stronger the feeling of weightlessness. This is why astronauts on a space shuttle experience a stronger feeling of weightlessness than someone on a rollercoaster.

4. Can weightlessness at the top of a vertical circle be experienced on Earth?

Yes, weightlessness at the top of a vertical circle can be experienced on Earth. This can be achieved through rides such as roller coasters or by performing parabolic flights in an airplane. However, these experiences are only temporary as the object will eventually return to experiencing the force of gravity.

5. How does the radius of the circle affect the feeling of weightlessness at the top of a vertical circle?

The radius of the circle does not directly affect the feeling of weightlessness at the top of a vertical circle. However, a smaller radius will require a higher speed to maintain the circular motion, resulting in a stronger feeling of weightlessness. Conversely, a larger radius will require a lower speed and therefore a weaker feeling of weightlessness.

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