Question

which statement explains how planets move in orbit as supported by newton’s first law of motion? planets can change the direction of their own orbital path. planets can change orbits due to their inertia. planets in motion will have a constant speed unless acted on by an outside force. planets with a greater mass will orbit more quickly than smaller planets.

Explanation:

Newton's first law of motion (law of inertia) states that an object in motion will maintain constant speed and direction unless acted upon by an external net force.

• The first option is incorrect because planets cannot change their orbital direction on their own; an external force would be required.
• The second option is incorrect because inertia keeps objects in their current state of motion, not change orbits.
• The fourth option is incorrect because orbital speed depends on orbital radius and the mass of the central body, not the planet's own mass.
• The third option directly aligns with Newton's first law, as planets' constant orbital speed is maintained unless an outside force acts on them.

Answer:

Planets in motion will have a constant speed unless acted on by an outside force.