# Questions tagged [escape-velocity]

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

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### Gravitational potential energy in Escape Velocity

From the derivation of formula of Escape Velocity we know that Minimum kinetic energy = Gravitational Potential Energy But in this circumstance, isn't it the value of gravitational potential energy ...
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### Is there an "escape velocity" for closed dimensions? [closed]

Assuming a closed universe, the shape of the universe is often considered, or at least presented in pop science, to be a glome (4-sphere), and popularly depicted as behaving analogously to a 3-sphere, ...
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### Escape velocity work done problem [closed]

We derive the formula of escape velocity by using conservation of mechanical energy, where we consider that work done by external force is neglected. But to provide the velocity to send an object to ...
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### Escape velocity from a rotating body depending on latitude

So the earth's escape velocity since the earth is rotating is dependent on the latitude. As stated in Wikipedia here: For example, as the Earth's rotational velocity is 465 m/s at the equator, a ...
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### Do black holes emit no light or does light fall back in black holes?

Black holes have such a strong gravity that escape velocity from it is more than speed of light which basically means nothing could escape it. Everything in the universe have escape velocity. For ...
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### How much energy is required to remove Earth from it's orbit and exit the solar system under perfect conditions?

Ok, this is my first question on this site. But it's one I've been thinking about for a while. Say through whatever means, we place a device capable of generating thrust/ kinetic energy on the surface ...
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### Escape velocity when Sun is present

When we calculate escape velocity for an object from earth, what we do is, we conserve energy. So if $v$ is the escape velocity, we write $$-\frac{GM_em}{R_e}+\frac{1}{2}mv^2=0$$ since we are assuming ...
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### Reason of object not leaving earth surface

The earth rotates around the sun at speed of approximately $18.5$ miles per second. And the escape velocity of earth is $6.96$ miles per second. So the speed of rotation is greater than the escape ...
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### How to calculate escape velocity of timelike particles in Schwarzschild Anti de Sitter spacetime?

From the geodesic equations, we can form something like $$\dfrac{1}{2}\left(\dfrac{d r}{d\tau} \right)^2 +V_{\text{effective}} = \tilde{E}$$ Since $\tilde{E}>0$ will correspond to unbound orbits, ...
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### Why must average velocity of a gas be 1/6 times escape velocity of planet for it to escape [closed]

I read this in my class textbook, and learnt the reason of absence of Hydrogen from atmosphere and Maxwell distribution curve from Physics stack exchange. But I am unsure of why should the average ...
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### Local escape velocity inside a sphere

For an astronomical body with arbitrary (but smoothly varying) mass profile, M(r), what would be the local escape velocity $v_e$(r) inside the body? Using this, I would like to estimate the escape ...
1 vote
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### Does Global Warming play any significant role in increasing velocity of atmospheric gases?

I understand that moon does not have an atmosphere because it's escape velocity is low and atmosphere gases if it had would escaped into vacuum. I know Earth has a relatively larger value of escape ...
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### A thought experiment on escape velocity [closed]

Note: air resistance will be ignored for this thought experiment. Suppose you hold a ball in your hands and have some kind of magical mechanism that allows you to begin accelerating upwards at a ...
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### Rail gun muzzle velocity

Don't know to ask it in this community or not but, is there any formula to calculate the muzzle(escape) velocity of rail gun? and another question We know that plasma is conductive so we can use ...
1 vote
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### Escape velocity for particle on pole of a rotating, spherical planet?

I got a book called "Problems and Solutions in Mechanics" and decided to try some problems. Here is problem 1008 Consider a rotating spherical planet. The velocity of a point on its equator ...
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### A clock falling at escape velocity; another blasting off at escape velocity

Imagine two clocks a distance $r$ from a non translating, non rotating planet. One clock is falling towards the planet at the escape velocity $v_e$ the other is blasting off from the planet at the ...
1 vote
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### Escape Velocity from orbit

I am a bit confused about the escape velocity formula. I know that escape velocity is $$V_\text{escape} = \sqrt{\frac{2GM}{R_e}} .$$ My question is does this equation change when for example I want ...
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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 $... 0 votes 3 answers 390 views ### Why we say that total energy should be zero at infinity in the derivation of escape velocity? I am little confuse about escape velocity. I have been taught that potential energy is arbitrary and hence we always assume it zero at infinity but actually it can or cannot be zero. My question is ... 0 votes 4 answers 155 views ### Is a planet's escape speed the same speed as in a circular orbit around it? I had this intuitive idea. An object shot upwards with the escape velocity must have the same velocity as the object has when it's in circular orbit at the same height as from where shot upwards ... 14 votes 2 answers 3k views ### If the escape velocity at the event horizon is the speed of light does it mean that slower bodies won't move away at all? If we say that the escape velocity from a planet is say 10 km/s we think that a slower body will move away from that planet but will be eventually forced to fall back on the planet. In simple words we ... 0 votes 1 answer 129 views ### Maximum height reached by an object Here, in the last line, from the formula s is negative, but how can s be negative? Also, should it not be s=u^2/2g instead of s= - u^2/2g? 0 votes 4 answers 163 views ### Have solar wind particles escaped the Sun's gravity or will they eventually return back? I've read that solar wind consists of hydrogen atoms that are, near the Earth, travelling at about 450 km/s. This is only 3/4 of the Sun's escape velocity, but then the Earth is also 150 million km ... 1 vote 0 answers 48 views ### Why is the escape "energy"$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)\... 0 votes 1 answer 63 views ### 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$... 2k views

### 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'...
1 vote
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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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### 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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### 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 ...
1 vote
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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 ...
1 vote
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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 ...
1 vote
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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 ...
1 vote
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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? ($... 0 votes 2 answers 1k views ### 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 ? -2 votes 1 answer 81 views ### 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 ... 0 votes 1 answer 113 views ### 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$11,200\; m/s$, ... 4 votes 4 answers 222 views ### 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? ... 4 votes 1 answer 54 views ### 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 ... 0 votes 1 answer 99 views ### 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 ... 