A Spaceship Is in Orbit Around the Earth at an Altitude

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.