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how does inertia and gravity combine to keep the planets in orbit?

how does inertia and gravity combine to keep the planets in orbit?

Public Comments

1. inertia is what keeps them from falling in, and gravity is what keeps them from flying away. The balance looks like an orbit.
2. From a planet as frame of reference (rotating coordinate system) gravitational force on the planet = centrifugal force on the planet
3. When we revolve a stone tied to a string, it always tries to move away along the tangent to the circle. This happens due to Inertia of direction i.e a body always tries to move in constant direction. The centripetal force applied to it keeps the stone from flying away along the tangent. Similar thing happens to planets in orbit. The inertia of direction tries, the planet to fly away in a straight line but the force of gravity(centripetal force) tries to keep them in orbit. So, a balance is setup b/w these two factors resulting in a beautiful orbit.