Home › WAEC WASSCE › Physics › Uniform Circular Motion and Gravitation › Kepler's third law relates the squares of the pe…
Kepler's third law relates the squares of the periods to which quantity?
AThe squares of the orbital speeds
BThe masses of the two planets
CThe cubes of the average distances
DThe squares of the average distances
Answer & Solution
Correct answer: C. The cubes of the average distances
1. Kepler's third law compares any two planets going round the Sun.
2. It sets the ratio of the squares of their periods equal to the ratio of the cubes of their distances.
3. So a planet further out has a longer year, and the law fixes exactly how much longer.
4. Using squares of distance instead of cubes would give the wrong period for every planet but one.
_Source: OpenStax College Physics (CC BY 4.0), Ch 6 "Uniform Circular Motion and Gravitation", section Kepler's Third Law_
Related questions
The Moon stays in orbit around the Earth. Which force provides its centripetal force?Why does a centripetal force change a body's direction but never its speed?A stone is whirled on a string in a horizontal circle. What supplies the centripetal forceUnder what condition does an ellipse become a circle?What does the line from the Sun to a planet sweep out in equal times?What shape does each planet's orbit about the Sun take, and where does the Sun sit?Besides muscle wasting, what else do astronauts lose in microgravity?What happens to an astronaut's muscles during a long stay in microgravity?