Lecture 10 – Motion and Gravity, Part 2/2
Summary / Checklist of the Main Concepts to Understand and Remember

Newton's Law of Gravity: Motion of Planets and Other Objects
•	According to Newton's law of gravity, what does the force of gravity between two objects depend on?
	According to Newton, how does the force of gravity change if I increase/decrease the masses or the distance between two objects?
	If I drop different objects in a place with gravity but no air, which ones will reach the floor faster?
	If more massive objects feel a stronger force of gravity, why do they all fall at the same rate when only gravity acts on them?
•	How does Newton's law of gravity explain what Kepler said about the motion of planets around the Sun?
•	Other objects that follow Kepler's laws because of gravity: Moons, asteroids, binary stars, satellites of galaxies.
•	Are there any objects that never feel a force of gravity, according to Newton's theory of gravity?
•	In the case of our Moon, to apply Kepler's laws should we use the sidereal month or the lunar/synodic one as its period?
•	Is there or isn't there a force of gravity in the International Space Station, as it orbits around the Earth?
Newton's Law of Gravity: Other Consequences
	Are the orbits of planets really exact ellipses, as Kepler said? Why or why not? Does the Sun move, as the planets orbit around it?
	Tides on Earth: What are tides due to?
•	How often do tides rise and fall at a location on Earth?
•	What do tides have to do with the fact that some comets break up when they approach a planet?
	What do tides have to do with the distorted shapes of galaxies close to each other?
	If we know the distance between two astronomical objects and their orbital period, what can we find out about them, and why?

Topics from the lecture page and textbook not listed above [or between square brackets] were not covered in class;
Underlined words indicate that I will expect students to remember a number or a name related to that topic.

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