An astronaut of inertial mass mi stands on a bathroom scale inside an elevator that accelerates upward at 2m/s2. Which statement correctly describes the physical quantity measured by the scale?
(a) The scale registers the product of the astronaut’s inertial mass and the elevator’s upward acceleration a only, since acceleration is what creates the extra force.
(b) The scale registers the normal force, which is proportional to the astronaut’s inertial mass.
(c) The scale registers the astronaut’s weight, equal to gravitational mass times g alone, regardless of the elevator’s motion.
(d) The scale registers the apparent weight, equal to the astronaut’s gravitational mass multiplied by (g−a) because the elevator accelerates upward.