Questions tagged [escape-velocity]

The velocity an object must travel to successfully exit the gravitational influence of a body.

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If the escape velocity for a body that is very close to a BH is near $c$ but not $c$ can it move away a little bit before it falls inside the BH?

The escape velocity from a common gravtational attractor means that a body lounched away from the attractor will never turn back. But in the case of a BH at the event horizon this escape velocity is $...
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Why we say that total energy should be zero at infinity in the derivation of escape velocity?

I am little confuse about escape velocity. I have been taught that potential energy is arbitrary and hence we always assume it zero at infinity but actually it can or cannot be zero. My question is ...
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Is a planet's escape speed the same speed as in a circular orbit around it?

I had this intuitive idea. An object shot upwards with the escape velocity must have the same velocity as the object has when it's in circular orbit at the same height as from where shot upwards ...
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If the escape velocity at the event horizon is the speed of light does it mean that slower bodies won't move away at all?

If we say that the escape velocity from a planet is say 10 km/s we think that a slower body will move away from that planet but will be eventually forced to fall back on the planet. In simple words we ...
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Maximum height reached by an object

Here, in the last line, from the formula s is negative, but how can s be negative? Also, should it not be s=u^2/2g instead of s= - u^2/2g?
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Have solar wind particles escaped the Sun's gravity or will they eventually return back?

I've read that solar wind consists of hydrogen atoms that are, near the Earth, travelling at about 450 km/s. This is only 3/4 of the Sun's escape velocity, but then the Earth is also 150 million km ...
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Is the speed of ejected particles proportional to the mass of the supernova star?

Is the speed of ejected particles proportional to the mass of the supernova star? Has the nuclear explosion more power if the supernova object has more mass? In simple words is it true that there is ...
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Why is the escape "energy" $e=1$ for a massive object in Schwarzschild metric?

Being $e$ the quantity found through Killing vector $(-1,0,0,0)$, $$e = (-1,0,0,0)\,\cdot\,(\dot{t},\dot{r},\dot{\theta},\dot{\phi})$$ For the Schwarzschild metric, $$e = \left(1 - \frac{2M}{R}\right)\...
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When is a moving test mass unbound from a black hole?

Imagine a small test mass $m$ with speed $v$ and distance $r$ from a Schwarzschild black hole of mass $M$. (The test mass is anywhere, but NOT on the horizon. Also, $m << M$.) What condition on $...
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Why does the value of the escape velocity approach 0?

I am a little confused about escape velocity. Does the escape velocity always approach 0 as we go to an infinitely far distance even if there isn't any friction? If so, why does it approach 0? Shouldn'...
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Would a projectile launched with the escape velocity reach a final velocity of 0 as time approached infinity?

I just wanted to check my understanding of escape velocity. If a projectile was to launch and have the exact velocity as the escape velocity of the earth, it would have a final velocity of 0 correct? ...
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Escape velocity at an angle near a black hole

What's the formula for the velocity required to escape at an angle (not normal) near a black hole? I know for example that the required velocity not to impact the black hole at $90$ degrees is larger ...
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Escape velocity at 45 degrees near a black hole [duplicate]

what if the formula for the escape velocity at 45 degrees compared to 90 degrees when you are near enough to a black hole for relativistic effects to become significant? I know that near enough to the ...
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What happens if a projectile is projected with escape velocity but not upwards?

This may be a dumb question, however I was confused with escape velocity and in the end determined that escape velocity is based off of energy, whereby (i think assuming air resistance and all that is ...
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$G$ expressed as a function of $c$?

The escape velocity for a given mass $M$ and a given radius $r$ is given by: $v_e = \sqrt{ \frac{2 G M}{r} }$ With $M$ = 25 kg and $r$ = 1/$c$ we have: $v_e = 1.0001917061 \approx 1$ Can we express $G$...
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Lift (elevator) and equivalence principle

A famous example to explain the equivalence principle is a lift (elevator) in the space (no gravity field), moving up with the acceleration of "g". It is said there is no way (experiment) ...
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Deriving a function of $r$ (distance from the planet's center) for velocity for a projectile launched beyond escape velocity

This is my first post here, and I'm here because I'm rather confused. I'm doing some homework at the moment and the question is asking for a function $v(r)$ which represents the velocity of a ...
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Can special relativity contain general relativity?

I realized that considering merely an upper limit for speed per se can hint at gravity(more precisely black holes). Very naively with Newtonian mechanics, one can derive the following formula for ...
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Can you jump off the counterweight of a space elevator at 1.2 x geostationary orbit? Is the assumption correct that an 80 kg person would weigh 2 kg?

Edit: This very silly question was answered in the comment by @pm-2ring - it's an orbit, you're weightless Can you jump off the counterweight of a space elevator (https://en.wikipedia.org/wiki/...
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1 answer
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Minimum mass of asteroid that could knock moon away [closed]

What is theoretically the minimum mass of asteroid, coming from deep space, that could knock the Moon away from Earth? The asteroid is not hitting the Moon, just interacting with it by gravity. I was ...
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Can you exit the event horizon with a rocket?

The reason given in most places about why one cannot escape out from an event horizon is the fact that the escape velocity at the event horizon is equal to the speed of light, and no one can go faster ...
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Question regarding Kleppner Kolenkow Example 5.5 "Escape Velocity—the General Case"

In example 5.5 from Kleppner Kolenkow (2nd edition), the general case of finding the escape velocity of a mass $m$ projected from the earth at an angle $\alpha$ with the vertical, neglecting air ...
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May a star explosion be in that way weak that the expelled material gradually recollapse and form the star again?

May a star explosion be in that way weak that the expelled material gradually recollapse and form the star again? My question is not about would that explosion leave a neutron star as a remnant but ...
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Black holes are not infinitely dense [closed]

If a black hole is infinitely dense, then therefore its terminal velocity in a determined field of gravity would be greater than the speed of light which is impossible, therefore a blackhole is not ...
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What would be the event horizon for charge?

If there was a sufficient charge density, would it be possible for that charge to have an event horizon, a radius at which a charged particle would need to be going faster than the speed of light to ...
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Would an anisotropic speed of light possibly allow light to escape a black hole?

It has been proposed that light coming toward the earth is near infinite but that light outgoing is near 1/2 c. I know we cannot directly measure the one-way speed of light, but if anisotropy were ...
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Why can you not use equation of motion $v^2 - u^2 = 2as$ when attempting escape velocity questions?

There is the this question: Imagine you are projecting a ball with $3/4$th the escape velocity from the surface of the earth. What is the farthest distance will it reach it from the centre of earth? ($...
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Is Acceleration of Earth Constant in its Orbit around the Sun?

According to this link , we can say that the Earth's acceleration is constant as the path is circular. But how ?
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Could a balloon be thrown from the moon to the earth by a man or woman or machine?

Is it physically possible for a three meter radius balloon to be whirled about on a string by a person or if necessary a machine (perhaps held by the person) standing on the surface of the moon and ...
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On figuring the eccentricity of an orbit knowing my launch speed [closed]

I want to check if I am reasoning a deduction correctly and am not missing some elementary part of the math. I have a rocket that I launch at $10,000\; m/s$. Earth's escape velocity is $11,200\; m/s$, ...
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Orbital escape velocity [closed]

Given a satellite (black) orbiting a planet (green) in a circular motion with $r_o$ being the orbital radius. The orbital the velocity of the satellite is $v_{orbit}=\sqrt{\frac{GM}{r_o}}$, right? ...
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How much of the Sun to not evaporate is due to gravity and how much due to magnetism?

As protons and electrons on the sun 'surface' have high kinetic energy something obviously should stop them to go away.Its gravity is very high compared to planets but is this enough as magnetism also ...
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Finding escape velocity considering two gravitational fields

A shuttle has to travel between earth and mars to a point $P$ where the gravitational force of each planet is equal. I need to calculate the energy required to reach the point $P$. I was thinking of ...
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Does time stop in black holes? [closed]

I was going through Hawking's incantations on black holes, where black holes get defined as follows: Black Hole: A region of spacetime from which the escape velocity exceeds the velocity of light. I ...
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If I had an initial upwards velocity and thrusted upwards to exactly counter-act gravity at all times, would I eventually escape Earth's gravity? [duplicate]

If I understand it correctly, the escape velocity of a body is the velocity I would need to escape that body's gravity if I did not continuously thrust against its gravity. So this question boils ...
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Does it take escape velocity to reach orbit?

I don't comprehend what is meant by "escape" The internet gives me two meanings thus my following ambiguity: Does escape velocity mean to reach infinitely far from the earth or to just reach ...
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Escape velocity from Earth and sphere of influence

I know that escape Velocity from the Earth's surface is 11.2 km/s. But is that the minimum velocity to get to orbit (L.E.O I guess) or to escape Earth's sphere of influence?
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Would a body have any residual velocity if launched at escape velocity from the Earth's surface?

A body is lanuched at escape velocity from the Earth's surface i.e 11.2 km/s ,what would be it's velocity outside the Earth's gravitational field? I guess it would be zero but there's another problem ...
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Is the escape velocity of black hole greater than the speed of light ? If not, then why does light can't escape the black hole? [duplicate]

I've heard different type pf answers for this qs and not really sure which one to go for.
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Really confused about orbital science

Okay let’s start straight away, What is Escape Velocity? Is it the speed required to get into orbit, or is it the speed required to escape the SOI (Sphere of Influence) of Earth completely? If it’s ...
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Escape Velocity, Misattribution, and Black Holes

Escape velocity is the ballistic speed required to escape from a gravitational field to infinity, ignoring any third body dynamics. The operative word here being ballistic, meaning unpowered. ...
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Why is the ratio between the escape velocities of different planets not the same as the ratios between their respective surface gravities?

Mars has a $g$ of about 38% of Earth's, but an escape velocity that is 45% of ours. Not a large difference, but there must be a reason.
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Can Binary Stars Escape Each Other?

updated 8/27/2020 While the recession of our Moon from the Earth may slow and even stop, (see When will the Moon reach escape velocity?) binary star systems will (1) never stop experiencing mutual ...
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Why does a planet with $v_c<v<v_e$ approach the sun faster than a planet with $v = v_c$

Not sure if I worded the question properly, but my question is about an image shown in Your Daily Equation #17 by Brian Greene He shows the following image: Where red is the case $v = v_c$ and green ...
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Escape velocity questions

This topic really screwed with my head in school and my teacher could never answer my questions so I thought I would ask here. I will break it down with mathematics and then logic. Let's assume we ...
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Escape velocity and Conservation of energy

If a physical body leaves earth with 11.2 km/s escape velocity with a certain amount of Mechanical energy, then how can it be said that the body will have 0 Mechanical energy at a point at infinity ...
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What equation can I use to calculate escape velocity as the radius increases from the Schwarzschild radius? [duplicate]

At the Schwarzschild radius, the escape velocity is the speed of light for all objects. However, I'm looking for an equation that will calculate the escape velocity as the radius of the object ...
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What is angle of escape velocity? [duplicate]

We know if a object has escape velocity (EV) it reaches space (ignore atmosphere friction), but at what angle. if an object travels parallel to earth surface with EV, will it escape curvature and ...
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Why can't light travel past the event horizon?

Since the event horizon is defined as the boundary within which the escape velocity is greater than the speed of light, and escape velocity is the speed required for that object to reach infinity away ...
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Where do the gases such as hydrogen and helium end up after leaving the earths atmosphere?

I've heard that gases like hydrogen and helium leak out of the earth's gravity a little by little. but where are they going? where do they end up after leaving earth's pull? would the sun pull them ...