A Spaceship Is in Orbit Around the Earth at an Altitude

question 25

Multiple Choice

A spaceship is in orbit around the earth at an altitude of 12 000 miles. Which one of the following statements best explains why the astronauts experience "weightlessness?"

• A)The centripetal force of the earth on the astronaut in orbit is zero newtons.
• B)The pull of the earth on the spaceship is canceled by the pull of the other planets.
• C)The spaceship is in free fall and its floor cannot press upwards on the astronauts.
• D)The force of gravity decreases as the inverse square of the distance from the earth's center.
• E)The force of the earth on the spaceship and the force of the spaceship on the earth cancel because they are equal in magnitude but opposite in direction.

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Definitions:

Life Span

The maximum duration of life of a species; in humans, the longest period that individuals of the species can live under optimal conditions.

Mortality

The incidence or risk of death within a population or group.

Resilience

The capacity to recover quickly from difficulties; toughness.

Presbycusis

Loss of acuteness of hearing due to age-related degenerative changes in the ear.