# Questions tagged [rocket-science]

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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### A thought experiment regarding elliptical orbits

Say I'm in a circular orbit around the Earth. I give my motor a burn in the tangental direction. My understanding is that my trajectory now becomes an ellipse, and if I want to enter a new, higher ...
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### Ideal Pattern of Thrust on rolling body [closed]

What Should be the idea pattern of switching a rocket engine attached to a rolling body on and off. So that it receives the maximum forward thrust. assuming that the ground has sufficient friction. ...
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### Which equation should be used to predict how much energy an Atmospheric Pulsed Laser Thruster would use?

I don't know if this should be asked on space exploration, worldbuilding or aviation, but I'm trying to figure out how much energy a pulsed laser thruster would use. The pulsed laser thruster would ...
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### Steep missile turn during launch?

I know this might be a pretty basic and easy question, but I've started to wonder about missile aerodynamics and how they work. I recently saw a video of a Tomahawk Cruise missile launch (linked below)...
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### A rocket problem solved using momentum conservation law [closed]

Suppose a rocket is fired upward with initial mass $m_0$ and it emits gas with mass rate $\alpha$ (.i.e $\frac{dm}{dt} = \alpha$). If $V$ is the gas speed in relative to the rocket, find the rocket ...
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### Why do the hydrogen-based jet engines create propulsion?

Theoretically, the jet engines create propulsion because of the pressure in the combustion chamber that creates force that pushes the rocket. But when hydrogen combustion is conducted, 2 hydrogen ...
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### A theoretical experiment about gravity and propulsion

An observer travels in a spherical ship drifting through space. The observer cannot 'see' anything outside the ship. At some time, the ship approaches a massive object P and describes an hyperbolic ...
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### Does a rocket moving in a circle expel exhaust at a greater velocity?

Consider a rocket undergoing constant acceleration in a rectilinear path. Assuming the rocket is ideal (ignoring fuel mass and energy loss such as sound, radiation, vibration, etc.) a portion of the ...
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### 3-stage rocket payload problem [closed]

A rocket goes to the sky, and undergoes 3 stages. I want to find the payload of it. In stage 1, 80% of the mass is the fuel, 10% of the mass is dry mass, and 10% is the remaining rocket. Similarly, in ...
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### Problem with equation of thrust in a system of variable mass

The equation for force on a system of variable mass (e.g. a rocket thrust equation) is $$F=-u\frac{\mathrm{d}m}{\mathrm{d}t}$$ where $u$ is the velocity of the escaping gases with respect to the ...
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### How torque and linear force interact with forces on poles

When there are 2 forces normal to each end of a uniform pole, if they had the same force, the rotation would be cancelled out and all force would be acting in one direction. But if one force was ...
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### Tsiolkovsky rocket equation assumptions

From what I understand, the elementary derivation of the Tsiolkovsky rocket equation makes the assumption that mass is lost as a linear function of time. Why do we make this assumption? Does it follow ...
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### Can I solve the drag equation without any experimental data? (I have a 3d model of a rocket and want to see how fast it can go using math) [closed]

I made a rocket in a cad software and tried to do the math to solve speed. Is there any way to solve the drag coefficient of a rocket (pointed for simplicity) cone and fins that goes up then goes to ...
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### How to find the length of a travel between planets using the Hohmann Transfer?

I am trying to figure out how long it would take to get from one planet to another. This is for a worldbuilding project of mine. I would put my question on the Worldbuilding Stack Exchange but I ...
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### What convention, if any, exists regarding the algebraic signs of constants and variables such as in this exercise?

This problem is from the original exercise set to accompany The Feynman Lecture on Physics. I am absolutely not asking how to find the solution. I am asking if there is some convention regarding the ...
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### Relativistic Rocket Equation Derivation

Could somebody help me derive this equation? $$\frac{\mathrm{d}M}{M}=-\frac{\mathrm{d}v(1-v_\mathrm{ex}\frac{v}{c^2})}{(1-\frac{v^2}{c^2})(-v_\mathrm{ex}\frac{v^2}{c^2}+(1-a)v+av_\mathrm{ex})}$$ This ...
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### Why are missiles rotating in space?

Watching the Starship launch today I noticed it's actually doing some full rotations. Why isn't it controlled? and why does it happen? I have read that it's the same for military missiles too
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### Why are NASA etc so good at hitting tiny targets in tiny time windows?

NASA have a tendency to arrive at targets that are so far away, within seconds of ETA, and statements like " it's like throwing an object from New York and having it hit a particular key on a ...
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### How is Newton's 3rd law applied in rocket propulsion?

I'm really wanting to get into physics more and I've had this question for a while. I do know a bit about rocketry as I think it's pretty cool but I'm still struggling to understand how Newton's 3rd ...
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### Rocket attached to a pendulum. How is energy conserved?

I'm trying to wrap my head around a conceptual problem involving a simple pendulum with a rocket attached to its mass. Imagine the rocket expels gas to provide a tangential thrust force. However, the ...
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### Okay, I know the risks. ( Amateur Rocket.) [closed]

I am currently attending a school for electrical science. A small group of students and our instructor are attempting group project to build a liquid fuel rocket. (I know it is a bit out of the scope ...
1 vote
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### Newton's 3rd law, force on a rocket

Please clear up this confusion for me: I just watched the video on khan academy @7:30 where the guy explains newton's 3rd law. He explains that for a box on a table, the forces equal out so it's at ...
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### How far can we go in space?

I'm a noob in physics & math, so I'm just looking for a scientific answer for a small fiction project. My question is : How far can we realistically go in space, if we managed to "use" ...
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### Is it possible to build electrical space engine based on Electromagnetic induction

Electromagnetic induction means magnet convert it momentum to an electrical current. So I wonder if it possible to use this phenomeno for making an enigne which will accelerate a magnet And the ...
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### Are there any equations for the mass of fuel (ejected at some velocity) required to propel a rocket of some mass some distance through gravity? [closed]

Either through constant gravity, more simply, or through the changing gravitational field, more accurately. This appears to be a fully determined system, although I found no analytic solutions for ...
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### Why does my perpetual CMBR rocket ship not work? Why does the CMBR have infinite energy?

Take a spaceship and accelerate it to 99.947% the speed of light, effectively blueshifting the Cosmic Microwave Background (CMB) from 1.9mm to 500nm, turning the CMB to a harvestable source of energy. ...
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### Time taken for a rocket to travel upwards [closed]

My doubt is a rather silly, simple one but i cant seem to understand what's wrong. Let's assume a rocket is moving up with a constant acceleration of a, is moving strictly vertically(no gravity turns, ...
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### Time taken for a rocket to reach a height [closed]

My doubt is a rather silly, simple one but i cant seem to understand what's wrong. Let's assume a rocket is moving up with a constant acceleration of $a$, is moving strictly vertically(no gravity ...
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### Efficiency Loss of Rocket Engine in a Vacuum Due to Underexpansion

A rocket engine in the vacuum will experience efficiency loss due to under-expansion in which the pressure of the exhaust is greater than the ambient pressure, which in a vacuum is near zero. How ...
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### Rocket Exhaust Ground Impact: Exhaust Gas Velocity vs. Pressure

Thanks for anyone that can help. Say we have a rocket engine in the vacuum of space with exhaust velocity of 2,000m/s or more, but low pressure exiting nozzle, say 1-2psi. A wider nozzle engineered ...
1 vote
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### Is it possible to attain (near) light speed in space?

As there is no drag in space/vacuum, is it possible to actually send a probe with enough fuel to have it achieve the speed of light or a value very near to it? Since there are not many significant ...
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### Rocket-assisted drag cancellation in artillery shell

The main limit on artillery range is drag. Hence for the same muzzle velocity, the WWII 800mm Schwerer supergun had twice the range of the modern 155mm M777 gun, because the super shell had a much ...
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### Physics of Landing a Rocket on a Specific Location [closed]

I have been working on a rocket model for the past year, and I have a question about the landing phase of the rocket flight. How do rockets, such as those from SpaceX, land on a specific location ...
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### Fluid dynamics of a balloon

This is a question which might not seem relevant to physics, but I was always curious if the shape of the balloon were to be not the shape that we all know of, when we release the tip will air flow ...
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### Total energy of a rocket launch

I'm wondering how the total energy of a combined Earth-rocket system is conserved in a rocket launch? Before launch, kinetic and gravitational potential energy of the rocket are 0. It then launches, ...
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### Would the acceleration of a model rocket be constant for a constant thrust or not?

The question is this: I believe the answer is A as the gravitational field strength becomes lower for larger distances of the object from the earth, but the model answer as as below: Are they ...
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### Propulsion of a spacecraft [closed]

If a craft is positioned at the strongest point of the earth's electromagnetic field being either positive or negative and the craft activates the same field it would repel each other would it create ...
1 vote
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