Gravity keeps a planet in orbit. Inertia tries to make the planet move in a straight line. The balance between the two makes the planet orbit a sun.
gravitygravity! a+
Inertia is a property of matter in which an object resists a change in motion.
Inertia makes things move.
The Earth's gravity is trying to pull the Moon towards the Earth. However, the Moon has inertia. It is trying to move in a straight line. If the Moon had no "sideways" velocity it would fall onto the Earth. In fact the Earth's gravity is needed just to bend the direction of the Moon's path and make the Moon orbit the Earth instead of flying off into space. This becomes clear if you do the mathematics, but that's the basic idea.
In space there is no gravity, so the planets can't fall down! The also stay on the same plane because they are attracted to the sun. They don't fall into the Sun because their speed is too great to let them fall straight in. The Sun's gravitational attraction only makes them curve towards the Sun as they move in their orbit. The force makes them take up elliptical orbits instead of just shooting away in a straight line.
gravitygravity! a+
centripetal force
centripetal force
it makes it go in a straight line
inertia
it makes it go in a straight line
The gravitational pull of the Earth pulls the moon toward us, but the inertia of the moon makes it want to travel in a straight path, the result is that it travels in a circle around us called an orbit.
The moon has inertia and wants to keep going in a straight line but the earth has a larger gravitational pull and wants to pull the moon towards it. This causes the moon to circle or orbit the earth.
inertia makes it want to fly straight but gravity makes it curve
inertia......
Inertia
it makes your hair very smooth and it keeps it straight