An astronaut and a large camera are floating together in deep space
PHYSICS · Multi-part · CBSE · Physics · System of Particles and Rotational Motion · System of Particles and Rotational Motion
Problem
An astronaut and a large camera are floating together in deep space, initially at rest relative to a nearby inertial reference frame. The astronaut (considered a rigid body) has moment of inertia Ia about a specified axis through her center of mass, and the camera (modeled as a rigid body) has moment of inertia Ic about the same axis when it is held at arm’s length, a distance r from the astronaut’s center. The astronaut suddenly releases her grip; the camera is given a short, gentle twist by the astronaut’s hands so that it begins to spin with angular speed ω0 relative to the astronaut.
Assume no external torques act on the two–object system during or after the release. Air resistance and gravity are negligible.
(a) Identify an appropriate system for analyzing angular momentum conservation in this scenario and justify your choice.
(b) Immediately after the camera is set spinning, the astronaut is observed to rotate slowly in the direction opposite the camera’s rotation. Explain qualitatively, without using equations, why the astronaut must rotate and why the directions are opposite.
(c) Describe how the angular impulse experienced by the astronaut compares in magnitude and direction with the angular impulse experienced by the camera during the brief twist. Explain the physical origin of this comparison.
(d) The astronaut later reaches out, grabs the camera, and brings it to rest relative to herself. Describe qualitatively what happens to the astronaut’s rotational motion during this second interaction and explain your reasoning in terms of angular momentum principles.