Kepler determined that planets change their speed as they travel around the sun. This happens due to all of the following EXCEPT
A). The sun's gravity makes the planets slow as they get closer
B). The sun's gravity pulls against the planet's inertia in some places
C). The sun's gravity pulls with the planet's inertia in some places
D). The planets' orbits are elliptical
D). The planets' orbits are elliptical
The correct answer is C). The sun's gravity pulls with the planet's inertia in some places.
Kepler determined that planets change their speed as they travel around the sun due to the following reasons:
A). The sun's gravity makes the planets slow as they get closer - This is true. According to Kepler's laws of planetary motion, as a planet gets closer to the sun, the gravitational force between the two becomes stronger, causing the planet to slow down.
B). The sun's gravity pulls against the planet's inertia in some places - This is true. Inertia is the tendency of an object to keep moving in a straight line unless acted upon by an external force. The sun's gravity pulls against the planet's inertia, causing it to change direction and speed.
C). The sun's gravity pulls with the planet's inertia in some places - This statement is incorrect. The sun's gravity and the planet's inertia do not work together in any places. The planet's inertia tends to keep it moving in a straight line, while the sun's gravity pulls it towards itself, causing it to follow a curved path.
D). The planets' orbits are elliptical - This is true. Kepler's first law of planetary motion states that the planets move in elliptical orbits around the sun. The elliptical shape of the orbit means that the distance between the planet and the sun is not constant, which affects the planet's speed.
To determine the correct answer, let's analyze each option:
A). The sun's gravity makes the planets slow as they get closer: According to Kepler's first law of planetary motion, also known as the law of orbits, planets move in elliptical orbits around the sun. Therefore, the planet's speed does change as it gets closer or farther from the sun. However, this option suggests that the sun's gravity makes the planets slower, which is incorrect.
B). The sun's gravity pulls against the planet's inertia in some places: Inertia is the tendency of an object to resist changes in its motion. The gravitational force exerted by the sun does act upon the planets, but it does not pull against their inertia. In fact, inertia keeps the planets moving in a straight line and the gravitational force acts as a centripetal force, redirecting the planets towards the sun.
C). The sun's gravity pulls with the planet's inertia in some places: This option is correct. As mentioned earlier, the gravitational force exerted by the sun acts as a centripetal force, directing the planets towards it. This force does work in the same direction as the planet's inertia, allowing the planet to travel in an elliptical orbit around the sun.
D). The planets' orbits are elliptical: This option is also correct. Kepler's first law states that planets move in elliptical orbits around the sun. The shape of the orbits and the varying distance between the planet and the sun contribute to the change in speed as the planet travels around the sun.
Based on the explanation, the correct answer is A). The sun's gravity makes the planets slow as they get closer.