- #1
fisico30
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Hello Forum,
a sleeping top, rotating fast on its vertical axis, will resist small perturbation, small torque that try to move the rotation axis away from the vertical: if the top is moved a small angle away from the vertical, it will act so that the axis quickly returns to the vertical position?
Why?
The small perturbation, small torque does not cause precession. Why? Is it because the perturbative torque only acts for a very short time and then disappears?
Still, why does the top manage to return to the vertical position?
A football tracking the parabolic trajectory responds the same way: the slight disturbance is such that the spinning ball, starting with zero initial torque, wants to maintain the zero initial torque condition and so moves its axis to align it to the trajectory.
What is the main principle that explains why there is this action by the football or spinning top?
thanks
fisico30
a sleeping top, rotating fast on its vertical axis, will resist small perturbation, small torque that try to move the rotation axis away from the vertical: if the top is moved a small angle away from the vertical, it will act so that the axis quickly returns to the vertical position?
Why?
The small perturbation, small torque does not cause precession. Why? Is it because the perturbative torque only acts for a very short time and then disappears?
Still, why does the top manage to return to the vertical position?
A football tracking the parabolic trajectory responds the same way: the slight disturbance is such that the spinning ball, starting with zero initial torque, wants to maintain the zero initial torque condition and so moves its axis to align it to the trajectory.
What is the main principle that explains why there is this action by the football or spinning top?
thanks
fisico30