Question

Which best explains why astronauts appear weightless when they are in a space shuttle orbiting Earth?

They are falling toward Earth at the same rate as the space shuttle.
They are falling toward Earth at a faster rate than the space shuttle.
They are too far from Earth to experience gravity.
They are too far from Earth to experience air resistance.

Answer 1

They are falling toward Earth at the same rate as the space shuttle.

Explanation: In orbit the shuttle and everything inside it are in continuous free fall toward Earth (gravity provides the centripetal force for the orbit). Because the astronauts and shuttle accelerate together, there is no normal force acting on the astronauts, so they appear weightless. (Gravity at orbital height is still large — weightlessness is due to free fall, not absence of gravity.)