The orbital radius of a satellite circling the Earth a. depends only on its mass and orbital speed b. depends only on its mass c. depends on its orbital speed d. is the same for all satellites e. is directly proportional to its orbital speed The acceleration of an object travelling with "uniform circular motion," is a. directed toward the centre of the circle b. directed tangent to the circle c. zero because the speed is constant d. changing in magnitude depending on its position in the circle e. directed outward from the centre of the circle Astronauts on board an orbiting space station appear to be "floating" because a. they are in the vacuum of space b. they are outside Earth's gravitational influence c. they are in free fall along with the space station itself d. they have become truly "weightless" e. they are pulled by the gravity of the moon