# Questions tagged [escape-velocity]

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

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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?

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 ...
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### Why in the formula to get the escape velocity $v_f$ is $0$?

The formula to get the escape velocity is: $$K_i + U_i = K + U$$ $$\frac{1}{2}mv^2_i-G\frac{mM}{R^2} = \frac{1}{2}mv^2-G\frac{mM}{r_\infty}$$ $$\frac{1}{2}mv^2_i-G\frac{mM}{R^2} = 0$$ My question is: ...
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### Escape velocity for electric field

As we know gravitational force and electric forces are quite similar I was wondering if there is minimum velocity called escape velocity required to escape gravitational field of earth so is there a ...
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### Why an object with a velocity of 11.2 km/s only enter space? [duplicate]

Can someone explain me what is escape velocity? why cant a bird with enough energy (super bird) fly into space?
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### Minimum Velocity for a projectile to leave the Earth

Let's say we have a cannonball that can shoot at various angles. How would we find the minimum velocity for this projectile to leave the Earth when the cannonball is shot at an angle $\theta$. I think ...
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### Can the acceleration of the object thrown by man exceed the acceleration of gravity? [closed]

Can the acceleration of an object thrown by man exceed the acceleration of gravity? I don't think so. Otherwise, how could the object fall back to the ground?
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### Doubt regarding derivation of escape velocity [closed]

In my text book the derivation goes like this: The minimum speed required to project a body from the surface of the Earth so that it never returns to the surface of the Earth is called escape speed. ...
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### Making a black hole using charge instead of mass?

You can just skip the background portion if you are interested in the real question. A bit of Background I was reading about gravity in my textbook and it mentioned about how in the recent years there'...
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### Could a planet have terminal velocity greater than its escape velocity?

I've had 2 semesters of college-level physics (1 of Mechanics and 1 of E&M) and was wondering after exploring a bit about terminal velocity: Is it physically possible for a planet to have a ...
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### Calculate escape velocity without using energy? [closed]

Is it practically doable to calculate the escape velocity on the earth not by using the principle of energy conservation, but by calculating the velocity of the particle as a function of time using ...
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### Escape velocity - Won't the orbital path just become larger with higher initial velocity?

Escape velocity is the minimum speed needed for an object to escape from the gravitational influence of a massive body. However, gravity has infinite range. Object $A$ is always getting pulled by the ...
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### Escape Velocity and its effect on the atmosphere

I’ve been doing some world building and wound up with a bit of a physics puzzle that’s stumped me. So rather than a long winded explanation I’ll simply state the primary parameters. Under otherwise “...
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### Answering simple questions about black holes to someone not knowing GR

In the Newtonian description of a black hole, it is a gravitating astrophysical object for which the escape velocity exceeds the speed of light in vacuum ($c$). But what does this actually mean for a ...
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### What if we set the exact equality $u^2=\frac{2GM}{R}$? Escape or not?

Let an object of mass $m$ is thrown up with an initial velocity $u$ from a spherical gravitating body $A$ of mass $M$ and radius $R$. Let us assume that when it reaches a height $h$ its velocity ...
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### How does General Relativity explain escape velocities?

In general relativity, objects follow the shortest possible path through curved space-time called a geodesic and that there exists no such force of gravity which pulls objects, it is just because ...
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### What is the escape velocity of a neutron particle (not neutron star)

I'm not sure if this question makes sense (if not maybe you can explain why) But if the neutron has mass and have a size, then it should have a escape velocity in the "surface" right? I know the ...
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### Gravitation and escape speed [closed]

I applied conservation of energy at the surface and at the centre of earth which brought me to equation $$- \frac{GMm}{R} =\frac{1}{2} m v^2$$ Having asked my sir, he said that gravitational potential ...
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### Escape velocity of Kerr black Hole [duplicate]

Do the event horizon of Kerr black Hole have escape velocity is equal to the speed of light same Schwarzschild black hole?
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### Could a rover drive to orbital velocity?

Could a rover, assuming it is on a perfectly smooth sphere in space, eventually reach orbital velocity? Would there be a limit on the possibile speed?
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### At what velocity will the moon be able to escape the earth's orbit?

I haven't found an answer to this question online so correct me if I am wrong. This is the escape velocity equation: $v_{esc} = \sqrt{\frac{2GM}{r}}$ and by plugging the known values, this is the ...
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### What would happen if a planet's escape velocity exceeded the speed of light?

What would happen if a planet's escape velocity exceeded the speed of light? Would it also collapse into a black hole (by Heisenberg's uncertainty principle and Pauli's exclusion principle) or would ...
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### I don't understand why escape velocity is necessary [duplicate]

I have read multiple explanations of escape velocity, including that on Wikipedia, and I don't understand it. If I launch a rocket from the surface of the Earth towards the sun with just enough force ...
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### Does space expansion mean the escape velocity at a black hole event horizon is strictly less than $c$?

The title pretty much sums it up. I could ask this question slightly differently; does the expansion of space cause the effective event horizon to shrink below what it would be for flat space? If so,...
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### How is it possible to escape a gravitational body? [duplicate]

The velocity required to escape a gravitational body is termed escape velocity. But how is it possible for any object to escape a body if it's gravitational field acts over an infinite range, so the ...
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### Why is escape velocity independent of direction of projection?

However, for any body projected with a velocity less then the escape velocity, the final maximum height will vary with variation in angle of projection. But why is this not the case in case of ...
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### Relativistic kinetic energy has no upper bound, so why is there a Schwarzschild radius?

Schwartzschild radius is the distance from the center of a body at which, the escape velocity will be equal to the speed of light, i.e. when $$\frac{2GM}{R} = c^2.$$ However, here it is assumed that ...
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### What is $R$ in the formula for escape velocity?

From the escape velocity formula $$v_e = \sqrt \frac {2GM}R.$$ Some sources say it is the distance between two objects with mass $M$ and $m$. Some examples I have read, only used radius of the $M$. ...
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How does this formula work, from a dimensional analysis perspective? $$v_\text{escape} = \sqrt{\frac{2GM}{R}}$$ The way I'm thinking about it is that $G$ is in units $\text{N} \cdot \text{m}^2/\... 2answers 2k views ### What is the difference between orbital velocity and critical velocity? Are their values similar or not? As critical velocity is the minimum velocity required to put a satellite into orbit. And orbital velocity is the velocity required to keep a satellite moving in an orbit.The value of critical velocity ... 2answers 315 views ### Is this derivation for schwarzschild radius for a black hole of mass$M$correct? Consider a body of mass$M$. We know that light can’t escape a black hole. Speed of light being the highest possible could be set as the escape velocity.(??) Then $$\text{Escape velocity}^2=(2GM/r)$$ ... 1answer 136 views ### What is the escape velocity in the Kerr metric? [duplicate] In the non-rotating Schwarzschild metric there is a straightforward expression for the escape velocity in the radial direction, defined from the point of view of a stationary observer at that radius, ... 6answers 4k views ### Can a massive object have an escape velocity close to$c$and not become a black hole? It is well-documented that a given body has a well-defined Schwarzschild radius, defining a minimum radius for its volume, given its mass, before it becomes a black hole. It is clearly true, also, ... 4answers 2k views ### Formula of escape velocity While establishing relation of escape velocity and radius , I confronted a problem . (i) $$v_e=\sqrt{\frac{2GM}{R}}$$ This states that$v_e$is inversely proportional to the square root of radius .... 1answer 436 views ### Length contraction in GR In general relativity,$\sqrt{1-v_{e}^2}$(with$v_e$the escape velocity as a fraction of the speed of light) is the factor by which time is dilated in a gravitational field. Is it also the factor by ... 3answers 177 views ### What could force Earth to leave the Solar System? [closed] Is it theoretically possible? I'm thinking of some possible ways, e.g 1) large enough asteroid hitting Earth; 2) asteroid, with bigger mass than Earth, with a high velocity passing very near Earth. 6answers 3k views ### Why is$v=\sqrt{\frac{GM}{r}}\$ not a valid equation for escape velocity?

Firstly, I know that the equation for the escape velocity is $$v_{\text{escape}}=\sqrt{\frac{2\,GM}{r}}\tag{1}$$ and understand it's derivation. The following is such a simple derivation; for a test ...
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### Is this definition of “escape velocity” correct? [duplicate]

According to Wikipedia: In physics, escape velocity is the minimum speed needed for an object to escape from the gravitational influence of a massive body. But, say, I have a spaceship in low ...
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### Is this the correct equation for Gravitational Potential Energy in Relativity?

If I understand correctly the equation for kinetic energy in relativity is $$E_k= mc^2 \left(\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}-1\right) \;,$$ and the equation for escape velocity in General ...