ACT Preparation / Unit 22 ACT 2124 short lesson, about 20 seconds
Gravity and Orbits
Captions available
The idea
Two masses attract with a force that grows with their masses and weakens with the square of their distance. Gravity holds planets and moons in elliptical orbits.
In practice
Doubling the distance between two objects cuts their gravitational pull to one quarter.
Where people slip
Gravity is mutual: by the third law, the smaller body pulls on the larger one exactly as hard.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
Unlocks
Something wrong in this lesson? Flag it · Sources for ACT Preparation