A thin, rigid square plate of side length 8.0 cm is mounted on a low-friction pivot…
PHYSICS · Multi-part · CBSE · Physics · Kinetic Theory · Kinetic Theory
Problem
A thin, rigid square plate of side length 8.0 cm is mounted on a low-friction pivot at its center inside a sealed chamber filled with an ideal gas at uniform temperature. A microbalance attached to the plate measures the instantaneous net force exerted by gas atoms on the plate. The plate can be rotated so that its surface normal makes an angle θ with a fixed horizontal direction.
During an experiment the measured magnitude of the net force exerted by the gas on the plate remains constant at 1.3×10−2N for every orientation of the plate.
Assume the gas is in equilibrium, the chamber walls are far from the plate, and edge effects are negligible.
(a) Describe qualitatively how the individual atomic collisions with the plate change as the plate is rotated from θ=0∘ to θ=90∘. In your description, discuss both the directions of the forces from the atoms and any changes (or lack thereof) in their magnitudes.
(b) Using physical principles, explain why the measured net force on the plate is independent of the plate’s orientation even though the directions of the microscopic forces vary with θ.
(c) The experimenter claims that the constant force reading implies the gas pressure inside the chamber is 2.0×102Pa. Evaluate this claim and justify your reasoning, explicitly stating any additional calculations or assumptions you make.