Here is the question, copied verbatim from the assignment:
You are sitting on a chair in the rotating co-ordinate system, going round and round. You are sitting at the centre of a turntable in fact. Directly above the turntable, a horizontal distance R from the centre of the turntable, and suspended from the roof of the non-rotating building the turntable is in, is a mass (1) on a string. Also, rotating with the table is a support from which a second mass (2) is suspended by a string.
An inertial observer sitting besides the turntable sees mass (1) stationary, its string hanging vertically. They see mass 2 going in circles and the string at an angle so that a component of the tension provides a net force pointing to the centre of the circle, hence providing the ‘centripetal’ force which allows the mass (2) to go in circles.
The rotating observer sees mass (2) being drawn to the outside by the centrifugal force. This observer sees ALL objects experience a force, the centrifugal force which is proportional to its mass and the distance from the axis of rotation ( rω2 eh?) so this is no surprise. This observer sees the mass (2) stationary with the centrifugal force cancelling the horizontal component of the tension. This rotating observer expects mass (1) to have a centrifugal force too, however this would point OUTWARDS. The rotating observer sees mass (1) to be going in circles which would require a net force to point INWARDS. How do we resolve this dilemma??
The Attempt at a Solution
i honestly don't know. the person going round and round sees a ball going around him. he expects to see a centripetal force that makes the ball go in circles. but he doesn't see the string at an angle. do i need to talk about pseudo-pseudo-forces? i mean really it's cause mass (2) just isn't moving in any frame, inertial or non-inertial, to begin with, so no one sees ANYTHING at all. the way i see it, it gravity and string tension, and nothing more, in no frame of reference anywhere. because it's not moving in ANY frame. but that's not right...how do i explain the fact that the string is not at an angle?