Special Area World Scholars Cup Practice Test

Gravity is the force that keeps planets in orbit around the sun. The sun’s gravity pulls inward on each planet, while the planet’s forward motion carries it sideways. If there were no forward motion, gravity would pull the planet straight into the sun; if there were no gravity, the planet would drift off in a straight line. The balance between these two effects—the inward pull and the forward motion—creates a curved path, or orbit. Space has very little friction, so there’s nothing to slow the motion and stop the orbit. Magnetism isn’t the force at work here, and inertia by itself would just carry the planet in a straight line without the inward gravitational pull to bend its path.