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RichardAK
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In answer to this question: \
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In answer to this question: \\\"Would you agree that we don\\\'t feel it because it\\\'s cancelled out by the force of the gravity of the Sun, just like the force of the string is cancelling out the centrifugal force acting on yo-yo, not letting it fly away?\\\" No, I would not agree. We don\\\'t feel any sense of centrifugal force because, in our frame of reference, the earth isn\\\'t moving. It\\\'s the same reason why, when you are flying in an airplane, and the plane is at cruising speed, it feels like the plane is standing still. In your frame of reference, it is.
The problem with your example of the person standing on a spinning ball is that if you\\\'re talking about, let\\\'s say, a circus performer balancing on a spinning ball no more than a meter across, the thing holding the acrobat at rest relative to the ball is just the force of friction between his feet and the ball. He\\\'ll have a sense of movement because he\\\'ll feel the air rushing around him as he spins, and he\\\'ll see faces in the audience turn into blurry lines, and so forth. To take another example, when you go to a show at a planetarium, they\\\'ll usually warn you before hand that you might feel a sense of motion sickness because of what\\\'s on the screen, but if you just shut your eyes, it will go away. The sensory perception of motion is what creates the sense of motion.
Technically, from the frame of reference of the circus performer falling off the ball, it was the entire universe spinning around him that made him lose his balance. You can use the frame of reference of Alpha Centauri if you want, or of the audience in the circus, and yes, from that frame of reference, he\\\'s the one spinning. But from that frame of reference, there is no centrifugal force at all. From that frame of reference, there\\\'s a centri\\\'\\\'petal\\\'\\\' force, provided by the friction between the performers feet and the ball. When he falls, it\\\'s because the centripetal force is not great enough to overcome the inertia of his lateral momentum.
Also, there can be no absolute rotation because all rotation is, at a certain level, revolution. When a sphere rotates around its axis, that means the molecules that compose the sphere are revolving around the axis. Furthermore, all revolution is really lateral motion. At any given instant, the molecules in the sphere are moving in a straight line tangential to their revolution. All motion is relative.
The problem with your example of the person standing on a spinning ball is that if you\\\'re talking about, let\\\'s say, a circus performer balancing on a spinning ball no more than a meter across, the thing holding the acrobat at rest relative to the ball is just the force of friction between his feet and the ball. He\\\'ll have a sense of movement because he\\\'ll feel the air rushing around him as he spins, and he\\\'ll see faces in the audience turn into blurry lines, and so forth. To take another example, when you go to a show at a planetarium, they\\\'ll usually warn you before hand that you might feel a sense of motion sickness because of what\\\'s on the screen, but if you just shut your eyes, it will go away. The sensory perception of motion is what creates the sense of motion.
Technically, from the frame of reference of the circus performer falling off the ball, it was the entire universe spinning around him that made him lose his balance. You can use the frame of reference of Alpha Centauri if you want, or of the audience in the circus, and yes, from that frame of reference, he\\\'s the one spinning. But from that frame of reference, there is no centrifugal force at all. From that frame of reference, there\\\'s a centri\\\'\\\'petal\\\'\\\' force, provided by the friction between the performers feet and the ball. When he falls, it\\\'s because the centripetal force is not great enough to overcome the inertia of his lateral momentum.
Also, there can be no absolute rotation because all rotation is, at a certain level, revolution. When a sphere rotates around its axis, that means the molecules that compose the sphere are revolving around the axis. Furthermore, all revolution is really lateral motion. At any given instant, the molecules in the sphere are moving in a straight line tangential to their revolution. All motion is relative.
