Zero gravity doesn’t mean that there is absolutely no gravity at all. It simply means that the centrifugal force is balanced out by the gravitational force.
Zero Gravity simulation chambers are chambers where one researches and develops components for actual space travel. It simulates the effects of zero-gravity, and gives the feeling of weightlessness.
-- A chamber simulating the effects of microgravity on Earth.
Roller Coaster Effect
Have you ever been on a roller coaster that goes upside down? Did you know that because you are going so fast the gravity that is pulling you towards the ground cancels out with something called the centrifugal effect. The centrifugal force is an apparent force that makes a body move away from a center of rotation. The amount of matter that is in your body propels you into the roller coaster track. Newton’s first law of motion states “An object in motion tends to stay in motion, unless another force acts against it.”
The wind resistances along the track are forces that work to slow down the carts, so that toward the end of the ride, the hills tend to be lower because the coaster has less energy to get them up. The inertia is what keeps you in your seat. Inertia is the force that keeps your body from moving. Although gravity is pulling you toward the earth, the acceleration force is greater than gravity, pulling upwards, counteracting gravity. When you go around a turn, a centripetal force keeps you from falling out of your seat. A centripetal force is the external force that allows the body to move in a curved path
-- The picture depicts the centripetal force that keeps you "seated" when you go upside down in a roler coaster.
For a plane to safely experience free fall, it must climb up at a steep angle, level off, and dive straight down. The centrifugal force that is exerted on the plane cancels everything out with its gravitational force. Due to air resistance because of the atmosphere, an object cannot be in free fall solely under the influence of gravity.
Airplane simulator simulates the zero gravity effect by going in a parabolic path, also called Keplerian Trajectory. On earth because of the air in the atmosphere, an object is under two forces; one gravity and two, air resistance. When the plane goes over the top of the arc, of the Kelperian trajectory is canceled by the gravitational pull of the Earth. The plane also shielded us from rushing in. So the passengers inside the plane experience free fall without the interference of air resistance. Typical time for the zero gravity effect is about half a minute.
-- Simulation of Gravity on Earth, following parabolic paths.
When an object dropped from the top of a tall building it experiences microgravity for about 2 seconds. There are many rides in amusement parks that are designed based on this principle.
Satellites and space stations circling Earth
Currently long-term micro-gravitational fields can be produced only on space stations and satellites circling Earth. In these the gravitational pull of Earth is exactly balanced by the centrifugal force to maintain their orbit. Absence of Earth’s atmosphere ensures that there is no air resistance to slow down the satellite.
Written By: Shreya