A circular demonstration platform in a physics classroom can be rotated about its…
PHYSICS · Multi-part · CBSE · Physics · System of Particles and Rotational Motion · System of Particles and Rotational Motion
Problem
A circular demonstration platform in a physics classroom can be rotated about its central vertical axis. Two identical coins are glued to the top surface: Coin A is placed 0.10 m from the axis, while Coin B is placed 0.25 m from the axis. Beginning from rest at a reference line, the platform is turned through an angular displacement of 120°. Assume the coins remain fixed to the surface throughout the motion.
(a) Without performing any numerical calculation, explain which coin travels through the greater linear distance during the 120° rotation and provide a clear physical reason for your choice.
(b) The platform is subsequently rotated through an additional 120° so that the total angular displacement is now 240°. Describe qualitatively how the combined linear distance traveled by Coin B compares with that of Coin A after the full 240° turn.
(c) Identify one key assumption about the motion of the platform or coins that is necessary for the reasoning in parts (a) and (b) to be valid.