The velocity an object must travel to successfully exit the gravitational influence of a body.
Questions tagged [escape-velocity]
210 questions
95
votes
5 answers
Does a gun exert enough gravity on the bullet it fired to stop it?
My question is set in the following situation:
You have a completely empty universe without boundaries.
In this universe is a single gun which holds one bullet.
The gun fires the bullet and the recoil sends both flying in opposite directions.…
JadaLovelace
- 1,449
55
votes
4 answers
Why doesn't hydrogen gas exist in Earth's atmosphere?
The root mean square velocity of hydrogen gas at room temperature is:
Gas constant: $R=8.31\ \mathrm{J\ K^{-1}\ mol^{-1}}$
Molar mass of hydrogen gas: $M=2.02\times10^{-3}\ \mathrm{kg/mol}$
$$\begin{align}
v &= \left(\frac{3\times8.31\ \mathrm{J\…
Bhushan Misal
- 579
49
votes
7 answers
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 than speed of light.
But, you don't really need…
Lahiru Chandima
- 613
26
votes
13 answers
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 gravity of object $B$ no matter the distance…
doge99
- 377
19
votes
2 answers
When will the Moon reach escape velocity?
From what I know, the Moon is accelerating away from the Earth. Do we know when it will reach escape velocity? How do we calculate this?
Grant Thomas
- 1,771
17
votes
6 answers
Why is there an escape velocity?
I've been trying for days, but I just can't understand why escape velocities exist. I've searched the web and even this site, and although I've read many explanations, I haven't been able to truly understand them. Most of the explanations I've seen…
Chris
- 273
17
votes
2 answers
What is the escape velocity of a Black Hole?
The escape velocity of Earth is $v=\sqrt{\frac {2GM}{R}}$, where $M$ is the mass of the Earth and $R$ it's radius (approximating it as a sphere), and is much less than light speed $c$.
But I want to know the escape velocity of black holes. Is it…
user11260
16
votes
5 answers
I don't understand why escape velocity is necessary
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 to overcome gravity, then the rocket will slowly…
Ambrose Swasey
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16
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5 answers
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, that the escape velocity for black holes is greater…
Isky Mathews
- 1,965
15
votes
2 answers
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 don't say the body won't move at all but it…
Krešimir Bradvica
- 2,295
15
votes
1 answer
Movie Interstellar - Question about Escape Velocity
The movie Interstellar shows people on a water planet where time is dilated so much that 1 hour is equal to 7 years back on Earth. Even though they lift off from Earth using a Saturn-V two stage rocket, they leave this water planet in a shuttle…
user32023
13
votes
3 answers
Does time stop in black holes?
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 am told that nothing in this universe can have a…
user288838
12
votes
1 answer
Escape velocity for Schwarzschild metric
I can't fill in the gaps in my solution to this and assistance or a reference would be appreciated.
The question begins with the straightforward derivation of the EoM for a massive particle orbiting in the equatorial plane, as
$$ \left(…
JCW
- 272
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11
votes
2 answers
How does escape velocity relate to energy and speed?
I have several confusions regarding escape velocity. I am sure I am missing something(s) obvious or maybe I am taught wrong.
Lets say we throw an object of any mass at exactly escape velocity of earth calculated from $v^2=\frac{2GM}{r}$ which is…
Suchal
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10
votes
5 answers
Can we escape Earth's gravity slowly?
I had a recent conversation with my girlfriend, who is a physics grad student. She was kind enough to listen to me rant about an idea concerning escape velocity. Unfortunately, I am still thinking about this question, but don't want to bother her…
Rick Scolaro
- 203