Question

what is the only force acting on an object orbiting earth?
air resistance
friction
inertia
gravity

Explanation:

• Air resistance: Objects in orbit (like satellites) are in space where there's negligible air, so no air resistance.
• Friction: In orbit, there's no surface contact for friction to act.
• Inertia: Inertia is a property (resistance to motion change), not a force.
• Gravity: Earth’s gravity provides the centripetal force needed for orbital motion, pulling the object toward Earth’s center, keeping it in orbit.

Answer:

D. gravity (assuming the options are labeled A to D with D being gravity; if the original options had different labels, adjust accordingly, e.g., if the last option is labeled as the fourth option, state that option: "the option with 'gravity'")