Topic 12 - Gravitational Fields

Question 1

Skylab was an early space station that orbited the Earth. Skylab contained a Body Mass
Measurement Device. This device was a chair connected to a stiff spring.

Astronauts in orbit about the Earth are sometimes described as ‘weightless’,
although they do experience a weight force.

Explain why astronauts may be described as ‘weightless’. (2 marks)

Answer 1

• The astronauts must experience a centripetal force as they orbit the Earth
• They do not experience (normal) contact forces