Colloquially referred to as one of the hardest professions, rocket science is actually a common name for spacecraft/space-systems engineering. However, one can also generalize this to include all forms of rocketry, including rockets that are not capable of space travel.

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At What Point Does Mass Cease to Matter?

I know very little about physics so I naturally have a lot of simple minded questions. Assuming I am piloting a rocket and want to obtain the fastest speed possible. At what point does mass more ...
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1answer
88 views

How to calculate the thrust of a rocket with relativistic exhaust

The general thrust equation is $F = \frac{dm}{dt}\cdot v$, where $m$ is propellant's mass and $v$ is the exhaust velocity, is the equation right? What if the propellant is highly relativistic? One ...
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2answers
15k views

What is the possibility of a railgun assisted orbital launch?

Basic facts: The world's deepest mine is 2.4 miles deep. Railguns can acheive a muzzle velocity of a projectile on the order of 7.5 km/s. The Earth's escape velocity is 11.2 km/s. It seems to me ...
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1answer
104 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 ...
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1answer
104 views

Conservation of energy during the flight of a fire cracker [closed]

We say that energy is neither created or destroyed. It can only be transformed. I hope this principle is applied in the flight of a fire cracker. The chemical energy is converted into physical energy ...
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1answer
130 views

Explain this contradiction of violation of “ energy conservation ” using classical mechanics

Consider a rocket moves upward with some acceleration for a very small time say '$dt$' then the kinetic energy increases (for acceleration). as well as as the potential energy increases (due to height ...
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0answers
17 views

Motion in Spaces [duplicate]

How does a shuttle move in the space as, the whole mechanism of a rocket is based on 3rd law of newton but, we can not apply 3rd law of newton in space because there is no reactive force in space?
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4answers
2k views

Could we launch a missile from a planet with the mass of Jupiter?

If the Earth had the mass of Jupiter, would we be able to launch a space missile ? Is there a formula to calculate how the launch of 1-Kg payload increases with gravity?
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2answers
194 views

The NERVA had to use liquid H2… But why?

The NERVA engine, developed at the late 60ies, was a nuclear thermal rocket developed for vacuum use in space craft. It was supposed to use Liquid Hydrogen, a cryogenic fuel with quite a few issues ...
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2answers
327 views

Can a nozzle increase the thrust of a water rocket?

First of all, what is the correct equation to determine the thrust produced by a water rocket? $$ F_T = \dot{m} V_e \tag{1} $$ $$ F_T = \dot{m} V_e + (p_e - p_0)A_e \tag{2} $$ Using the first ...
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0answers
50 views

Finding position with respect to time along a trajectory across a sphere (orbital mechanics)

When trying to find an object's position with respect to time on a ballistic trajectory along a curved surface, what equation should I use? I know that when adding force to an object to achieve the ...
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1answer
140 views

The Lagrangian of a Rocket

I am trying to understand how to write the Lagrangian of a system which consists of a rocket losing gas mass in a rate of $\frac{dm}{dt}$, the gas moving in a velocity of $u_0$ in the rocket's view? ...
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2answers
90 views

How much fuel do I need to send cubesat 1kg from Earth orbit to Moon orbit? [closed]

How much fuel do I need to send cubesat 1kg from Earth orbit to Moon orbit? And how much stages? For i.e. C12H22O11 + KNO3, polyethylene + oxygen or kerosene + oxygen.
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0answers
42 views

Earth to LEO, gravity drag and potential energy

A lot of references indicate takes about 9.4 km/s of delta-v to reach LEO. https://en.wikipedia.org/wiki/Low_Earth_orbit#Orbital_characteristics The delta-v needed to achieve low Earth orbit ...
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3answers
153 views

What sort of propulsion technology would allow spaceships to lift off the surface of the Earth and ascend into space like we see in sci-fi movies?

In many sci-fi films, spacecraft are easily capable of lifting off the surface of a planet like a Harrier and ascending into space. It's clear that the propulsion system/jet engines aren't your ...
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3answers
2k views

Where does the energy go in a rocket when no work is done?

While playing Kerbal Space Program, I wondered where my chemical energy would go when fired at 90° to the motion. It would do no work on the rocket, but all that energy has to go somewhere, right? ...
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2answers
328 views

Trying to modify the Tsiolkovsky rocket equation for the real world

Everyone knows about the famous Tsiolkovsky rocket equation. However, he formulated the equation neglecting many things. So, here, I am trying to find the real equation. My thinkings: Suppose, the ...
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1answer
250 views

Rocket projectile motion problem [closed]

I'm not really sure where to start with this question: In a brisk wind from the south-east of $14.1\:\mathrm{m/s}$ a rocket pointed due north is launched from a cliff that is $500\:\mathrm{m}$ above ...
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1answer
132 views

Constant Jerk Relativistic Rocket [duplicate]

A quick google search will give many helpful pages and calculators regarding constant acceleration relativistic rockets, but my question is somewhat different. What if jerk is the parameter to be ...
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1answer
63 views

Reading about liquid propellant rocket design

I was reading NASA's manual on liquid propellant rocket design from 1971. It makes the following statement. The rocket or, in a more general sense, the reaction motor presently is the only ...
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2answers
229 views

How to calculate thrust from opening a pressure vessel in space?

One popular trope in science fiction is the astronaut who (deliberately or inadvertently) punctures an air tank or something and goes rocketing off. How would we calculate the amount of force that ...
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3answers
884 views

Does an ion thrust engine consume more energy as it speeds up?

This question goes to a very basic non-understanding of mine that I have had in the back of my mind for ages - I just read the following here: ion thrusters are capable of propelling a spacecraft ...
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1answer
43 views

Molecular analysis of Rocket propulsion

Newton's third law states,For every action exerted by an object A on object B,there will be an equal and opposite reaction on A. In case of rockets,during ejection of hot gases with high velocities,...
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3answers
637 views

Why are rockets launched vertically?

Why the rockets mostly used for space missions are launched vertically upwards and not horizontally like an airplane carrier, gradually increasing its altitude, wouldn't that be more efficient?
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1answer
2k views

Using nuclear devices to terraform Mars: Elon Musk's nuclear proposal? [closed]

Elon Musk has recently suggested Using nuclear devices to terraform Mars. In the past, comet related ideas were mooted, but Musk seems, to me anyway, to be a man in a hurry and perhaps his idea has ...
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4answers
475 views

Would it be economical to add a counterweight to rocket launches?

It seems a large amount of rocket fuel during launches is spent to get the mass moving; indeed according to QuickLaunch, Inc. it takes 40% of the rocket fuel to get to Mach 1.3. It seems as though the ...
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3answers
4k views

Why do we launch rockets during the day?

The clips that I have seen of rockets launching all seem to be carried out during daytime. However, we learnt at school that rockets are fired closer to the equator and towards the east to take ...
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1answer
437 views

Water bottle rocket: Where does the energy go without water?

In Portland's OMSI there is a hands-on water bottle rocket station. (https://www.youtube.com/watch?v=cdtmVY76_PQ). The rockets are normal PET bottlers. The visitors fill their bottle with an amount of ...
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2answers
74 views

Rockets and distance [closed]

I am trying to create an equation which allows for me to change the aspects of the rocket so i can calculate the distance traveled vertically. My idea is for a rocket that only moves vertically; ...
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1answer
59 views

The Real Rocket

Suppose we have a Rocket with initial mass $M_o$ and we want to sent it into space. The equation of motion is (i think... please tell me if there is something i forgot) $$\frac {d(mu)}{dt}=-mg-\frac{...
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6answers
5k views

Halley's Comet as a “Free Taxi”

Now that the ESA has landed a probe on a comet, namely Rosetta's Philae Probe, could we possibly land a probe on Halley's comet? Fuel seems to be a limiting factor for interstellar expeditions - could ...
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2answers
184 views

Thrust in space without expelling mass

The classic rockets move losing their mass in one direction and moving to the other direction. Thinking about an alternative engine where we lose very small mass. This is how the engine works The ...
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1answer
95 views

What are the biggest reasons that Cars get higher Land Speed Records than motorcycles'? [closed]

What are the biggest reasons that Cars get higher Land Speed Records than motorcycles'? It is because cars have a more streamlined frame than than motorcycles? But, from pictures, it seems that doesn'...
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1answer
72 views

Rocket thrust over time [closed]

I have calculated the thrust of a rocket, and it's burn time for an orbital manoeuvre. I need to know how much force is applied on the rocket every half-second. How would I go about doing this? ...
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1answer
51 views

Asteroid as a “free slingshot?”

The question Halley's Comet as a "Free Taxi" had an interesting thought, even though it didn't work out. I was wondering about a variation on the idea. Use a cable, as illustrated below. Could this be ...
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1answer
75 views

Rocket velocity during fuel burn [closed]

I know the formula for the velocity of a rocket after the on board fuel has been used up: $$ \Delta v = v_{ex} \ln\left( \frac{m_i}{m_e} \right) - gt $$ where: $v_{ex}$ is the exhaust velocity $...
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2answers
648 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 ...
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2answers
199 views

Does the outflowing water create a thrust on the bucket?

Let's consider the the bucket with water, which has a small hole at the bottom. Let the bucket lift up with a constant force $\vec F$. Water in the bucket, of course, flows out of it. Questions are ...
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1answer
179 views

How many days it takes to travel to Cygnus? [duplicate]

BACKSTORY I read today newspaper and made discovery of planet Cygnus (in news paper of course :v) that human can live there! The distance is 1400 Lightyear. Assuming I travel with the world fastest ...
6
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2answers
269 views

Saturn V F-1 engines and beyond

I read that the F-1 engine from the 1st stage of the Saturn V rocket is the most powerful engine ever created by mankind, delivering ~200 gigawatts of power. Thus, I have got two questions: Will ...
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5answers
5k views

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 ...
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3answers
180 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: $$...
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1answer
91 views

Rocket equation derivation, question about signs

My question is about signs in the derivation of the rocket equation. Considering a rocket of mass $m$, its momentum at time $t$ is $p(t)=mv$. At time $t+dt$ it ejects a quantity $dm$ so its momentum ...
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0answers
70 views

What's the fastest you can slingshot from one black hole to another? [closed]

Let's say you have your spaceship orbiting around a black hole. Its orbital velocity is arbitrarily close to the speed of light (or you can just set it to c*0.99 if it makes it easier.) There is ...
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0answers
47 views

What factors are influencing a woosh rocket?

Not sure if this is too much chemistry, but I'll try: If I fill a plastic bottle with a small amount of rubbing alcohol, shake it around and hold a match to the bottle neck, I'll get a flame wooshing ...
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85 views

Rotational dynamics equation for a variable mass system?

I'm searching for the formulation of Euler's rigid body dynamics in the case of a variable mass system. I'm reading the book Mechanics of Flight by Warren F. Phillips (2nd edition) and unfortunately ...
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2answers
506 views

Velocity of Rocket Exhaust

i recently learned a bit of rocket propulsion.It wasn't much complex but was explained in simple terms.The only problem i had understanding it was that in calculating the thrust of rocket the velocity ...
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2answers
638 views

“Suicide Burn” rocket problem [closed]

THIS IS NOT HOMEWORK. I'm actually in Physics I atm, and am an avid player of Kerbal Space Program. I hope to do my CS masters thesis several years from now on something space related. But none of ...
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2answers
131 views

Is it possible to reach outer space with this method? [duplicate]

Could we use a hot air balloon to carry a rocket and send it into orbit at a higher altitude? That is, do I need to reach a specific speed to be completely free of Earth's gravity, or can I just ...
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57 views

A simple detailed book on how/why model rocket engines and parachutes work

I'm planning on getting a model rocket in the near future to fire off w/ my 2 daughters (9 and 11). I'm going to require first that they learn how/why rocket engines and parachutes work (so they can ...