How much speed is required by an object to escape earth's gravitational pull ?

Question

What do rockets, spacecraft, and all, push against in outer space to gain forward momenuum? A vacuum provides no resistance.

Has anything ever left Earth's atmosphere on its own (i.e. No help from human rockets, etc.)?

Answer 1

assuming you neglect air resistance and consider only the effect of gravity then by conservation of energy
kinetic = gravitational
mv^2/2 = GMm/r
so
v = √2GM/r ≈ 11200m/s ≈ 40300km/h ≈ 25100mi/h

rockets don't push against anything, they spit fuel out at such a fast rate that it propels them forward, like the recoil of a gun except instead of shooting out one bullet at a time they shoot out a continuous stream of burnt fuel

light leaves the earths atmosphere all the time without help
...The moon was once part of the earth, but this was helped by the collision of a huge asteroid and I'm sure a lot of smaller rocks have been ejected during similar collisions but I guess they can't be really be counted as leaving on there own.

the end
.

Answer 2

What allows the rocket to lift off is not speed but Power. The power of the rocket must be greater than the Gravity power pushing down the Rocket. in order to get off the Ground.
As the rocket accelerates and reaches the velocity 11.1924km/sec the gravity pressure on the rocket becomes neglible and is considered to have escaped the maximum effect of acceleration toward the Earth.
However theoretically no matter how far the rocket goes gravity field is still there relative to the earth.As The field of gravity is relative ;Therefore obeys the rules of Relativity.
What you says in order to move in space you need something to push against in order to move. This is correct its the law of collision In Newton's 3rd Law of motion.
Your observation about vacuum offering no resisance would then violate Newton's 3rd Law if Space did not contain any substance.
That is why the Ancient Wisdom postulated that there exists a substance in space that acts as the pushing point in order to move.That pushing point was called the Aether.
Therfore if there exist an Aether in the Universe it would offer resistance for the rocket in space to push against.
If the rocket was pushing against an empty vacuum due to Newton's Law it just simply would not be able to move.

Has anything left the atmosphere and the solar system to go to Heaven without the help of rockets.? Yes.
It hapens all the time when Humans pass away to go to Heaven.
However we do not know enough about those who go to Hell.

Answer 3

Escape velocity is about 22,900 miles per hour - that'll get you off and away from Earth, but still trapped in the solar system.

A rocket works on action/reaction. If you're in space, and you have a brick - you throw it one way, and you'll go another. Throw 10 bricks, and you increase your speed. Now, a rocket burn is basically a controlled explosion; The force of that explosion is what is pushing your space craft a particular direction.

Well, nothing is going to leave the atmosphere without *some* kind of force. There *have* been meteors big enough to slam into the Earth and ejecting lots of little rocks out into space, possibly even giving them escape velocity. (We found meteors on Earth that were originally from Mars, for example.) Earths' a lot bigger, so the chances of a rock hitting us and sending fragments out at escape velocity are smaller, however.

Answer 4

> How much speed is required ...

The required speed, called "escape velocity", is about 7 miles per second. Once you've reached that speed, you can shut off your rocket engines, and your leftover momentum will allow you to literally coast away from the earth forever--hence the term "escape."

Note that (contrary to popular misconception) you do NOT need to reach escape velocity in order to get into ORBIT around the earth. Orbital speed is in fact smaller than escape velocity by a factor of sqrt(2). (For the earth, that is about 5 miles per second.) Orbital speed will keep you going in a circle. Escape velocity will take you OUT of the circle and take you ever farther away from the earth.

> What do rockets, spacecraft, and all, push against ...? A vacuum provides no resistance.

The rocket fuel itself provides the "resistance." Isaac Newton said that whenever you push against something, it always pushes back on you. This is true whether the thing you're pushing against is locked in place (like a wall), or movable (like gases in a rocket engine). The very act of thrusting the gases out the back end, causes a "recoil" effect which pushes the rocket in the opposite direction.

> Has anything ever left Earth's atmosphere on its own...?

Very large (nuclear-sized) explosions can provide enough momentum to small rocks to throw them into outer space. This has undoubtedly happened in the past when the occasional asteroid would hit the earth.

Answer 5

there is an amount of speed that we say escape velocity of a planet or star and it relates to the mass and gravity of that planet or star the earths escape velocity is 11.2 meters per second so if you throw a stone with this velocity up it escapes and doesnt trap in the orbit.for the second question i must say that the propolsion system of rockets and fighter jet planes dont demand air to do their job they just thrust gases out behind them and relating to newton laws it goes forward.for the third question i must say no maybe just molcules of atmosphere escape.nothing can escape but theres a theory about cration of the moon that says that sth hit the earth and a big rock took off and went out but you see also moon is still in orbit.

Answer 6

Escape velocity is roughly 25,000 mph

They push against air, ever-thinning air, as they leave the atmosphere. There is still air even in the upper part of the atmosphere.

No, nothing has left Earth without assistance.

Answer 7

Rockets don't push against anything. They throw off hot gasses and are propelled by the force of the hot gas against the upper surface of the inside of the rocket motor.
Action and reaction.

Answer 8

From the surface of the Earth, the theoretical escape velocity for any object is about 11.2 kilometres per second or nearly 25,000 miles per hour. From elevations in orbit it is less because the pull of gravith is less.

Answer 9

I think you will need to calculate how fast the earth is moving across the sun and the earth's orbit and do some mathematical computation and you will get your answer

Answer 10

Escape Velocity is something on the order of 17,000 Miles Per Hour and depends upon which direction you launch your rocket...one direction gets you a boost from the Earth's rotation, the other direction requires more velocity to achieve Escape Velocity because you are moving against the rotation of the Earth. In the latter case I think Escape Velocity is about 20,000 Miles Per Hour.

One of the laws of physics states that for every action, there is an equal and opposite reaction. Something to push against is not required, as your learned experiences on Earth might suggest. Try this...Locate a really good chair on easy rolling wheels. Place the chair on a really smooth, flat floor. Have someone assist you to catch the things you are about to throw... Now, sit in the wheeled chair with your feet curled up underneath you, holding three 1 Gallon Plastic Bottles of Water. One at a time (feet up in the air, not touching the floor) throw the jugs to your assistant friend. Your chair will scoot across the floor with little blasts of force each time you throw a bottle. EQUAL AND OPPOSITE REACTION.

Now, if, instead of throwing bottles of water, you had a rocket engine bolted to the chair, you would shoot across the room really fast and bang into a wall...air in the room, or not. Space ships move forward this way...blasting hot exhaust gases out the rear of the rocket causes the rocket ship itself to move forward with an equal and opposite force.
EQUAL AND OPPOSITE REACTIONS.

Last Question: NO.
Things like balloons have gone up into the fringes of space for brief periods to altitudes of around 125,000 Feet but eventually they came back down. Space is somewhere between 50 and 100 Miles up. Those balloons went up about 25 Miles, which is quite high, but not Space. Some form of propulsion must drive you up to that altitude and keep driving you upward and away at high velocity (17,000 to 20,000 Miles Per Hour) or you will fall back to Earth due to the pull of gravity. That efort requires a trememdous amount of thrust and once out into space it can only be sustained by a rocket engine which has everything it needs to continue running (lack of oxygen in space) in zero atmosphere conditions. You could not, for example, use a really big Jet Engine. It would flame out at some particular altitude due to lack of oxygen. Thrust power would cease at that point.

The trick here is to stop trying to understand things about space in direct correlation to things you have learned on Earth. Space is entirely different and the rules change out there.

Final example of things being different... On Earth, you could take a rifle and pick out a target, aim at it, and shoot with a pretty fair chance of hitting what you aimed at.

In space, you could take a rifle, pick out a target, aim at it, and not have any chance at all of hitting it...because all things in space are moving. You would have to figure in lead distance based upon the speed of your target, and the speed of your rifle bullet. The same situation was faced by submariners shooting torpedoes at moving war ships. Submariners used gadgets called TDC's (Target Data Computers) to do the math quickly and produce the correct angle of fire which would place the torpedo in calculated contact with the moving war ship...unless something changed.

Hunters do the same thing when aiming a shotgun well ahead of a flying duck so that the shotgun pellets and the duck arrive together at the same place at the same time. Pellets strike duck...duck drops from the sky...Etc.

Aim your rifle at the Moon and you will never hit it...A) The Moon is moving at more than 2,000 Miles Per Hour and 240,000 Miles away. B.) Your rifle bullet is not traveling at 17,000 to 20,000 Miles Per Hour, so it will fall back to Earth. Do the math...good rifle bullets travel at about 2100 feet per second...that is 1432 Miles Per Hour...Not even close to the 17,000 Miles Per hour Escape Velocity.