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I am standing (wearing crampons) on a perfectly
Chapter 9, Problem 9.19(choose chapter or problem)
I am standing (wearing crampons) on a perfectly frictionless flat merry-go-round, which is rotating counterclockwise with angular velocity Q about its vertical axis. (a) I am holding a puck at rest just above the floor (of the merry-go-round) and release it. Describe the puck's path as seen from above by an observer who is looking down from a nearby tower (fixed to the ground) and also as seen by me on the merry-go-round. In the latter case explain what I see in terms of the centrifugal and Coriolis forces. (b) Answer the same questions for a puck which is released from rest by a long-armed spectator who is standing on the ground leaning over the merry-go-round.
Questions & Answers
QUESTION:
I am standing (wearing crampons) on a perfectly frictionless flat merry-go-round, which is rotating counterclockwise with angular velocity Q about its vertical axis. (a) I am holding a puck at rest just above the floor (of the merry-go-round) and release it. Describe the puck's path as seen from above by an observer who is looking down from a nearby tower (fixed to the ground) and also as seen by me on the merry-go-round. In the latter case explain what I see in terms of the centrifugal and Coriolis forces. (b) Answer the same questions for a puck which is released from rest by a long-armed spectator who is standing on the ground leaning over the merry-go-round.
ANSWER:Step 1 of 3
(a) As seen by a ground-based observer, the puck has initial velocity \(\Omega R\) in the tangential direction.
Since it is subject to zero net force, it travels in a straight line at constant speed (left picture). As seen from the merry-go-round, the puck is subject to the two inertial forces (centrifugal and Coriolis). It is initially at rest, so the Coriolis force is initially zero, and the puck is accelerated outward by the centrifugal force. As it speeds up, the Coriolis force becomes increasingly important and the puck curves to the right, spiralling outward.