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What does the line from the Sun to a planet sweep out in equal times?
AEqual angles at the Sun
BEqual areas of the orbit
CEqual lengths of arc
DEqual changes of speed
Answer & Solution
Correct answer: B. Equal areas of the orbit
1. Kepler's second law concerns an imaginary line drawn from the Sun to the planet.
2. That line sweeps out equal areas in equal intervals of time.
3. Near the Sun the line is short, so the planet must move quickly to sweep the same area.
4. Far from the Sun the line is long, so a slower motion sweeps out the same area.
_Source: OpenStax College Physics (CC BY 4.0), Ch 6 "Uniform Circular Motion and Gravitation", section Kepler's Second Law_
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