An astronaut is inside an orbiting spacecraft that circles Earth in a nearly circular…
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
An astronaut is inside an orbiting spacecraft that circles Earth in a nearly circular path at an altitude where the magnitude of the local gravitational field is about 8.7Nkg−1. Inside the spacecraft, the astronaut and a nearby tool kit are both observed to float freely in mid-air.
Assume the spacecraft, astronaut, and tool kit can each be treated as separate point masses unless otherwise stated.
(a) Describe, in words, all the forces (if any) acting on (i) the astronaut and (ii) the tool kit while they are floating inside the spacecraft.
(b) Explain why the astronaut experiences a sensation commonly referred to as "weightlessness" even though Earth’s gravitational force on the astronaut is not zero at this altitude.
(c) Compare the apparent weight of the astronaut while floating in the orbiting spacecraft with the apparent weight the same astronaut would measure while standing at rest on a scale on Earth’s surface. Justify your comparison in terms of the physical origin of apparent weight.
(d) Identify the essential condition that must be satisfied for any object to be truly weightless, and discuss how that condition is met in the scenario described.