Linked Questions

13
votes
5answers
4k views

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 ...
0
votes
2answers
154 views

Masslessness of the electromagnetic field

Why is the electromagnetic field massless? I presume the mass term in the Lagrangian, $$ \dfrac{1}{2}M^2 A_{\mu}A^{\mu}, $$ would "violate" gauge redundancy. But this is what its name indicates: ...
2
votes
3answers
115 views

If fuel was provided by an autonomous side ship, how much fuel would be required for a 10 metric tons rocket to reach the ISS?

The point here is that the rocket weight should never include fuel. It can take off from any departure base of your choice. The fuel provided by the side ship would then be used only to lift the ...
2
votes
1answer
195 views

What percentage of a rocket fuel is used to lift fuel itself?

I don't need an exact number, also it can be to travel to the ISS or the moon, it's not important. I just want to get an idea of how much fuel is used in a «recursive» sort of way. Edit: I am asking ...
0
votes
2answers
1k views

How much fuel is needed for a constant-acceleration rocket?

My son and I have been discussing the concept of a constant-acceleration rocket, as described here and here. We're willing to assume advanced technology such as a fusion rocket, which, according to ...
0
votes
3answers
383 views

Conservation of momentum for rockets [closed]

I'm reading Kleppner & Kolenkow Example 4.16 on page 140-141 of the second edition and I am confused by something. So we have a rocket in free space. No friction and no gravity. The rocket has ...
2
votes
0answers
133 views

How efficient is rocket engine clustering?

So I watched a video where a guy built his own rocket from scratch. I noticed he used some F15-0 rocket engines* to get this thing as high as 300m (he's built other rockets too, where he used the same ...
1
vote
0answers
35 views

I would like to know why they make rockets so big [duplicate]

Why are rockets so big? I mean wouldn’t it be easier to make them smaller for flying to the moon? So, why large?
2
votes
1answer
293 views

Understanding rocket equations [closed]

I'm doing a science project where I have to explain the physics behind a trip to an exoplanet and I also have to explain about rocket equations while doing so. I know that a trip to an exoplanet is ...
0
votes
2answers
2k views

How does a rocket's exhaust gas' momentum propel a rocket?

During the launch of a rocket into space, the exhaust gases from the engine possess momentum. Outline, with the help of an equation, how this causes the rocket to be propelled upwards. Can someone ...
1
vote
3answers
402 views

Intuition behind Ideal rocket equation

If a rocket expels propellant at a velocity of $v_e$ decreasing its mass from $m_0$ to $m_1$, then according to the Tsiolkovsky rocket equation the change in velocity of the rocket ($\Delta v$) is: $$...
0
votes
4answers
842 views

Which is the right explanation for rocket motion? [duplicate]

What actually causes a rocket to move? Is it the pressure in the rocket engine or the amount and velocity of mass that is being ejected out. The reason I am asking is, I found these two explanations ...
3
votes
1answer
133 views

Why was the asteroid 101955 Bennu chosen by the NASA OSIRIS-REx sample return mission?

Please explain it in simple terms. Why was THIS asteroid chosen among all the thousand of asteroids?
6
votes
2answers
2k views

Why do rockets jettison fuel tanks? [duplicate]

I'm trying to understand why rockets have multistages releasing their fuel tanks. Say a rocket $R$ has two fuel tanks $A$ and $B$, which respectively have masses $m_a$ and $m_b$, and the mass of the ...
1
vote
2answers
3k views

Is there an upper limit to a rocket's size/payload? [duplicate]

It's obvious that as you increase the payload of a rocket, you need to also increase the amount of rocket fuel. Yet, as you increase the amount of rocket fuel, you are also increasing the overall mass ...

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