Lesson 5: Orbits and Gravity
An orbit results from gravity continually changing the direction of a moving object. The Moon, planets, and satellites provide examples, while comparisons between worlds show the difference between mass and weight.
Key Ideas
- Gravity pulls objects toward one another. Earth’s gravity keeps the Moon nearby.
- Gravity’s pull depends on how much mass objects have and how far apart they are. Moving the same objects farther apart weakens the pull.
- Mass is how much matter an object contains. Weight is how strongly gravity pulls on it.
- An object in orbit keeps moving forward while gravity bends its path around another object.
- The Moon keeps falling toward Earth, but it also moves sideways. Together, these motions keep it traveling around Earth.
Vocabulary
- Mass: The amount of matter in an object; mass stays the same no matter where you are.
- Weight: The measure of gravity's pull on an object; weight changes depending on where you are.
- Inertia: An object stays still or keeps moving in a straight line at the same speed unless a push or pull changes its motion.
- Orbit: The curved path an object follows around another object, such as the Moon’s path around Earth.
Discussion Questions
- If orbiting is just falling in a curved path, are you technically falling right now? Explain your reasoning.
- Satellites in lower orbits actually travel faster than satellites in higher orbits. Why do you think that is?
- If the Moon's gravity is one sixth of Earth's, what might that mean for an astronaut's health on a long Moon mission?
I highly Recommend watching this video but ignoring the text (it's advanced). Just watch for the general things you've learned about in this lesson.