friction from the atmosphere the velocity of the shuttle the mass of the shuttle gravity from Earth
I gave my students this multiple choice question: When a space shuttle orbits Earth and returns home, a force opposes its motion. What is the source of the opposing force?

Only one answer is correct among these 4 choices:
- friction from the atmosphere
- the velocity of the shuttle
- the mass of the shuttle
- gravity from Earth

Could you tell me which one is correct?

friction from the atmosphere