What is the escape distance of Earth’s gravity and if the Earth’s gravity can hold a spaceship in a fixed orbit, why wouldn’t there be a little gravity on the ship as well?
Escape distance of Earth's gravity
The escape distance of Earth's gravity is the distance at which an object must be from the center of Earth to escape Earth's gravitational pull. The escape distance is approximately 40,270 kilometers (25,020 miles) from Earth's surface.
Earth's gravity can hold a spaceship in a fixed orbit, why wouldn't there be a little gravity on the ship as well?
Earth's gravity does indeed pull on spaceships in orbit. However, the spaceships are also moving very fast, so they are constantly falling towards Earth, but at the same time, they are also curving away from Earth due to their tangential velocity. This interplay of forces results in the spaceship being in a fixed orbit.
Inside the spaceship, astronauts experience weightlessness because they are falling at the same rate as the spaceship. This means that there is no net force acting on them, so they feel weightless. However, Earth's gravity is still pulling on them, just as it is pulling on the spaceship.
In summary, Earth's gravity does pull on spaceships, but the spaceships are moving fast enough to escape Earth's gravity. Inside the spaceships, astronauts experience weightlessness because they are falling at the same rate as the spaceships.
The Earth's gravity will always pull on an object, no matter how distant. Gravity is a force that obeys an 'inverse square law'. So, for example, put an object twice as far away and it will feel a quarter of the force. Put it four times further away and it will feel one-sixteenth the force. Escape velocity is the minimum speed needed for a free, non-propelled object to escape from the gravitational influence of a massive body. The escape velocity from Earth is about 11.186 km/s (6.951 mi/s; 40,270 km/h; 36,700 ft/s; 25,020 mph; 21,744 km) at the surface. You need to travel roughly 62 miles upward to leave Earth's upper atmosphere, but be traveling at approximately 25,000 mph to break free from the gravitational pull of the Earth. The Earth's gravitational field extends well into space it does not stop. However, it does weaken as one gets further from the center of the Earth. Classical gravity falls off with 1r2, so there isn't really a point where it becomes "negligible" unless you choose an arbitrary cutoff point beyond which something is "negligible". You could of course escape from earth's gravity if you could continuously move at even a very low speed. The problem is maintaining this speed against the pull of gravity. To do so you would need to introduce some other force, at which point the concept of escape velocity is no longer applicable.Outer space does not begin at a definite altitude above Earth's surface. The Kármán line, an altitude of 100 km (62 mi) above sea level, is conventionally used as the start of outer space in space treaties and for aerospace records keeping. If the Earth's gravity did just suddenly disappear we would no longer have a force keeping us on the ground. The Earth would keep spinning, as it does, but we would no longer move with it; instead we would move in a straight line, upwards. The force of gravity decreases as the inverse of the distance-squared. This force drops to zero at a distance of infinity. Therefore, Earth will always pull on a spacecraft, regardless of its distance from Earth. On Earth, astronauts feel the force of gravity as weight, because Earth's surface prevents them from falling. In outer space, however, there is no ground to push against astronauts. As they orbit and fall toward Earth at the same rate as their spaceship, astronauts feel weightless, as if there were no gravity. A spacecraft in orbit is not beyond the reach of Earth's gravity. In fact, gravity is what holds it in orbit without gravity; the spacecraft would fly off in a straight path. As the spacecraft orbits, it is actually falling, though it never reaches the ground. Falling in circles around a planet instead of smashing into it doesn't seem like the gravity we're used to on earth, but it's the exact same kind of falling. Astronauts in orbit around the earth are not experiencing "no gravity". They are experiencing almost all of earth's gravity, but with nothing to stop them. Gravity affects the motion of spacecrafts in Earth's orbit by keeping them in a nearly circular path around the Earth. The force of gravity is what keeps a spacecraft in orbit, rather than allowing it to fly off into space. The strength of the gravitational force depends on the mass of the object and the distance between the object and the center of mass of the object it is orbiting. In the case of a spacecraft orbiting the Earth, the gravitational force is provided by the Earth and the spacecraft has to move at a certain speed, called orbital velocity, in order to overcome the force of gravity and maintain its orbit. The initial speed of the satellite maintained as it detaches from the launch vehicle is enough to keep a satellite on orbit for hundreds of years. A satellite maintains its orbit by balancing two factors: its velocity (the speed it takes to travel in a straight line) and the gravitational pull that Earth has on it. Astronauts orbiting in space feel a sense of weightlessness because there is no external contact force in space pushing or pulling upon their bodies. Gravity is the only force acting upon their body. Gravity being an action-at-a-distance force cannot be felt and therefore would not provide any sensation of weight. The volume of the ship is so great that its ratio of mass to volume is less than that of water. The buoyant force pushing up on the ship is equal to the gravity pulling the ship down. This is why the ship floats.
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