Rocket Definition and 1000 Threads

A rocket (from Italian: rocchetto, lit. 'bobbin/spool') is a projectile that spacecraft, aircraft or other vehicles use to obtain thrust from a rocket engine. Rocket engine exhaust is formed entirely from propellant carried within the rocket. Rocket engines work by action and reaction and push rockets forward simply by expelling their exhaust in the opposite direction at high speed, and can therefore work in the vacuum of space.
In fact, rockets work more efficiently in space than in an atmosphere. Multistage rockets are capable of attaining escape velocity from Earth and therefore can achieve unlimited maximum altitude. Compared with airbreathing engines, rockets are lightweight and powerful and capable of generating large accelerations. To control their flight, rockets rely on momentum, airfoils, auxiliary reaction engines, gimballed thrust, momentum wheels, deflection of the exhaust stream, propellant flow, spin, or gravity.
Rockets for military and recreational uses date back to at least 13th-century China. Significant scientific, interplanetary and industrial use did not occur until the 20th century, when rocketry was the enabling technology for the Space Age, including setting foot on the Earth's moon. Rockets are now used for fireworks, weaponry, ejection seats, launch vehicles for artificial satellites, human spaceflight, and space exploration.
Chemical rockets are the most common type of high power rocket, typically creating a high speed exhaust by the combustion of fuel with an oxidizer. The stored propellant can be a simple pressurized gas or a single liquid fuel that disassociates in the presence of a catalyst (monopropellant), two liquids that spontaneously react on contact (hypergolic propellants), two liquids that must be ignited to react (like kerosene (RP1) and liquid oxygen, used in most liquid-propellant rockets), a solid combination of fuel with oxidizer (solid fuel), or solid fuel with liquid or gaseous oxidizer (hybrid propellant system). Chemical rockets store a large amount of energy in an easily released form, and can be very dangerous. However, careful design, testing, construction and use minimizes risks.

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  1. A

    Different acceleration in an accelerating rocket?

    I read from a physics website that says that an accelerating object experiences different acceleration throughout its structure according to special relativity. I never thought of that! "In special relativity, one finds that when a spacecraft maintains its structural integrity, so that the...
  2. B

    Deriving Thrust from Newton II for Rocket Motors

    Homework Statement Derive from Newton II the thrust (the force produced by the rocket exhaust) achieved by a rocket motor which ejects material with constant velocity u and mass ejection rate a. Homework Equations The Attempt at a Solution Not sure...I know how to derive vf =...
  3. F

    Rocket Launch-Horizontal and Vertical motion:

    Homework Statement Does changing the thrust(amount of gunpowder) in the rocket alter both the horizontal and vertical speeds? Homework Equations I worked this bit out Rocket A has less gunpowder and horizontal motion was 8m/s Rocket B with more gunpowder was 10m/s [b]3. The...
  4. F

    What was the acceleration of the rocket?

    Homework Statement A rocket moving towards Alpha Centuari at 1000ms^-1 fires its rockets, accelerating backwards at a constant rate for 5 minutes. During this 5 minutes, the rocket moved 240km close to the star. What was the acceleration? Homework Equations I have no idea what formula you...
  5. G

    What is the mass of water ejected per unit time from the nozzle in a toy rocket?

    Homework Statement A toy rocket consists of a plastic bottle which is partially filled with water. The space above the water contains compressed air. At one instant during the flight of the rocket, water of density p is forced through the nozzle of radius r at speed v relative to the nozzle...
  6. B

    How High is the Rocket When the Canister Hits the Launch Pad?

    Homework Statement You are working as an engineer in a space company. During launches, rockets often discard unneeded parts. A certain rocket starts from rest on the launch pad and accelerates upward at a steady 3.30m/s2. When it is 235m above the launch pad, it discards a used fuel canister by...
  7. T

    How Is the Rocket's Acceleration Calculated After the Parachute Opens?

    Homework Statement What is the acceleration of the rocket at a time of 5seconds after the parachute opens. Homework Equations F=ma The Attempt at a Solution I simply thought the acceleration would be 9.8m/s/s
  8. S

    Rocket Exhaust Gases: Initial & After 29s Acceleration

    A rocket with initial mass of 7.30×103 kg is fired in the vertical direction. Its exhaust gases are ejected at the rate of 6.00×101 kg/s with a relative velocity of 2.100×103 m/s. What is the initial acceleration of the rocket? What is the acceleration after 29 s have elapsed?
  9. P

    What is the maximum model rocket altitude?

    Hi I have a few question i don't understand how to complete. Homework Statement A model rocket leaves the ground, heading straight up at 49m/s. a)What is the maximum altitude?What are its speed and altitude at b)1s c)4s 2. Homework Equations ( For all questions) Constant acceleration...
  10. M

    How Does a Faulty Model Rocket's Motion Change Over Time?

    [b]1. A faulty model rocket moves in the xy-plane (the positive y-direction is vertically upward). The rocket's acceleration has components a_{x}(t)= \alpha t^{2} and a_{y}(t)= \beta - \gamma t, where \alpha = 2.50 {\rm m}/{\rm s}^{4}, \beta = 9.00 {\rm m}/{\rm s}^{2}, and \gamma = 1.40 {\rm...
  11. O

    Maximum altitude of a rocket in 2D motion and free body motion

    Homework Statement A rocket is launched at an angle of 53 above the horizontal with an initial speed of 75 m/s. It moves for 25s along it's initial line of motion with an overall acceleration of 25 m/22. At this time its engines fail and the rocket proceeds to move as a freebody. a) What...
  12. S

    Find Max Velocity & Altitude of Rocket: Mass, Thrust, Burn Time

    what equation would i use to find the max velocity and max alt of a rocket. the probem gave me mass of rocket (g), mass of engine (g), mass of propellant (g), average thrust of engine(Newtons), burn duration of the engine (seconds). i got an example which is massrocket=23,mass...
  13. H

    Rocket problem: Newton's 2nd Law

    Homework Statement In this problem we explore a slightly more realistic model of a rocket's acceleration still neglecting air resistance. Consider a rocket fired straight up from rest burning fuel at the constant rate of b kg/s. Let v=v(t) be the velocity of the rocket at time t and suppose...
  14. A

    What is the maximum momentum of a rocket with given exhaust speed and mass?

    Homework Statement A rocket that starts at rest with mass M ejects exhaust at a given speed u. what is the mass of the rocket(including unused fuel) when its momentum is maximum? Homework Equations p=mv The Attempt at a Solution well basically i used conservation of momentum to get...
  15. M

    The velocity and height of a rocket launched vertically from the earth.

    Homework Statement So if a rocket is launched vertically from the surface of the earth, the rocket has a mass of 1000 kg and has a fuel load of 12000 kg. The fuel burns at such a rate that it will be exhausted after 180 secs. The exhaust velocity of the burned fuel relative to the rocket is...
  16. M

    How can I calculate the velocity and height of a rocket at burnout time?

    Hello! I'll pose the question first: A rocket is fired straight up, burning fuel at the constant rate of b kilograms per second. Let v=v(t) be the velocity of the rocket at time t and suppose that the velocity u of the exhaust gas is constant. Let M=M(t) be the mass of the rocket at time t...
  17. S

    Linear Momentum: Rocket Explosion

    Homework Statement A 975-kg two-stage rocket is traveling at a speed of 5.80 x 103 m/s with respect to Earth when a predesigned explosion separates the rocket into two sections of equal mass that then move with a relative speed (relative to each other) of 2.20 x 103 m/s along the original line...
  18. L

    Finding max height and speed before it hits the ground of a rocket

    Homework Statement A model rocket initially at rest on the ground is fired vertically upward, and the engine thrust produces a constant acceleration a = 40 m/s2. After running for 2.5 s the engine is cut off and then the rocket is in free fall. (a) Find the maximum height that the rocket...
  19. C

    Rocket Acceleration and Altitude Calculation

    (I apologize in advance if this should have been merged with my other topic. Homework Statement A 1000kg weather rocket is launched straight up. The rocket motor provides a constant acceleration for 16s, then the motor stops. The rocket altitude 20s after launch is 5100m. You can ignore any...
  20. J

    Rocket problem (time is wrong )

    rocket problem (time is wrong!) Homework Statement A test rocket is fired vertically upward from a well. A catapult gives it an initial speed of 80.0 m/s at ground level. Its engines then fire and it accelerates upward at 4.00 m/s^2 until it reaches an altitude of 1000m. At that point its...
  21. P

    Rocket travels along parabolic path (RECTANGULAR COMPONENTS)

    Homework Statement When a rocket reaches an altitude of 40m it begins to travel along the parabolic path (y-40)^2=160x, where the coordinates are measured in meters. If the component of velocity in the vertical direction is constant at vy=180m\s, determine the magnitudes of the rockets...
  22. E

    How High and Far Does a Spring-Propelled Space Shuttle Travel?

    Homework Statement The Lower Machiavellian Space Shuttle, having a total mass of 3500kg, is about to make its' debut launch. Rather then using a rocket engine to launch the shuttle, the Machiavellianans' use a large compressed spring, having a spring constant of 1600N/m. If the spring can be...
  23. D

    Calculating Momentum Change for Rocket Course Alteration

    Hey, I've been having trouble with the following question, and I've tried all I can think of and still can't get it. Your help is much appreciated. "A rocket with a total mass of 3700kg is traveling in outer space with a velocity of 110m/s towards the sun. It wishes to alter its course by...
  24. J

    Understanding liquid fueled rocket engines

    I'm troubled by the problem of pumping fuel to a combustion chamber. The big problem is that pressure cannot be directed in some particular direction. So when you see propellant leaving the chamber with a great pressure, it should be kept in mind that the propellant is attempting to leak, with...
  25. M

    Rocket Acceleration: Calculating Speed and Altitude

    Homework Statement A 1000kg weather rocket is launched straight up. The rocket motor provides a constant acceleration for 16s, then the motor stops. The rocket altitude 20s after launch is 5100m. There is no air resistance. Questions: What was the rocket's acceleration during the...
  26. M

    Kinematics Plane and Rocket Problem

    Homework Statement Some plane is flying at an altitude of 12.0 km above sea level and is flying in a straight line at 850km/h. The plane then drops a rocket. After the drop the plane maintains the same altitude and speed and continues to fly in a straight line. The rocket falls for a brief...
  27. S

    How does a rocket work in space

    when there is nothing for the reaction force to push on? My textbook says, ironically rockets work better in space because in atmosphere it has to do work against the pressure thingy. But it doesn't explain why, all it says is "at the microscopic level its complicated" I remember asking...
  28. C

    Rocket ship speed and relativity

    ok I know that nothing with mass can travel at c but i have to ask this question. if I am in a rocket ship traveling at .5c and another rocket ship is traveling at .5c in the opposite direction then am I traveling at c relative to him . Probably Galilean transformations don’t work in this...
  29. T

    Looking for Rocket Nozzle Equations

    Howdie. This may not be the forum for this, but I am having trouble finding a forum on rocket science. Specifically, it is easy to find various equations for rocket chamber and nozzle design, but they all leave out the crucial equations that relate parabolic nozzle, divergent section...
  30. J

    \Seeking Value for Saturn V Rocket Drag Coefficient

    Hi, just found these forums, and they look very useful. I'm a second year Aerospace Engineering student, and as part of a project I'm modelling the first stage of a Saturn V rocket. I'm using a linear and non-linear model, and have all the equations sorted out. The only problem is I can't...
  31. B

    Can Computational Flow Dynamics Predict the Performance of CO2 Rocket Cars?

    Hi All Hope this is the right forum, I am looking for an applied approach! I am interested in modelling the behaviour of CO2 powered rocket cars. These small models are powered by releasing pressurised carbon dioxide from a “sparklet” cylinder. The model cars race along 24 metre long...
  32. Rasalhague

    Antimatter rocket v. black hole starship

    In http://arxiv.org/abs/0908.1803v1" , 2003, Robert Frisbee offers some ideas on the design of an antimatter rocket. Crane and Westmoreland concentrate more on the possibility of a black hole starship, rather than the size or shape of the craft. I'm wondering, how many of the constraints that...
  33. Artlav

    What causes the formation of beads in rocket exhaust plumes?

    Not sure if it's chemistry or physics, but the latter seems more like it. Let's take a look at pretty much any large rocket with smoke-less exhaust during it's launch, for example the recent one: As you can see, there are a kind of beads in the exhaust plume at seemingly constant...
  34. D

    How Do You Calculate Rocket Motion Parameters Over Time?

    Hi there I'm having a bit trouble understanding the rocket motion and how the find the velocity, acceleration and travelheight as a function of time. First, i assume that the velocity of the ejected mass relative to the rocket is constant. Secondly, i assume that the rocket mass changes with...
  35. P

    Calculating the Initial Vertical Acceleration of a Saturn V Rocket

    Homework Statement A Saturn V rocket has a mass of 2.75x10^6 Kg and exerts a force of 3.3x10^6N on the gases it expels. determine the initial vertical acceleration of the rocket. 2. The attempt at a solution heres my attempt... F=3.3x10^6N Fg= M=2.75x10^6 Fnet-MA F-Fg=ma F-mg=ma...
  36. L

    When the rocket reaches its maximum height, what is its kinetic energy?

    [b]1. A model rocket with a mass of 4.3kg is launched straight up at a speed of 65m/s. Kinetic energy when it takes off is 9083.75 J. Total energy when it takes off is also 9083.75J. When the rocket reaches its maximum height, what is its kinetic energy? [b]2. KE(kinetic energy)=1/2MV^2...
  37. J

    Help me put this rocket into orbit Need a jumpstart

    Homework Statement Ok so i had all of this typed up and some work typed out and then the page refreshed and i lost it all so this one is going to be shorter and more brief. I have to create a spreadsheet and graph of altitude vs time and speed vs altitude. My goal is to place a rocket into a...
  38. P

    Speed of a Rocket far from Earth

    Homework Statement A rocket is launched straight up from the Earth's surface at a speed of 1.60×10^4 m/s. What is its speed when it is very far away from the earth? Homework Equations F= (GMm)/r^2 G= 6.67 X 10^-11 M= 5.98 X 10^24 Potential Energy = (Gm1m2)/r Kinetic Energy =...
  39. N

    Water Rocket - Rate at which water exits

    Homework Statement We're currently studying Momentum & Collisions and Work and Energy Use algebra – no Calculus I’d appreciate help in setting it up. I seem to be missing one equation since I keep coming up with two unknown variables. A water rocket (2-liter half filled with water...
  40. L

    What Initial Velocity Does a Rocket Need to Reach 5000m?

    Question reads: A rocket of mass 1000 kg is being fired to a height of 5000m. The rocket engine shuts off when the rocket reaches a height of 1000m, and the rocket coasts up to 5000m. a) what velocity must the rocket have at the 1000m point to enable it to reach 5000m ? b) what acceleraation...
  41. A

    What Is the Initial Mass of a Two-Stage Rocket With Given Parameters?

    Homework Statement okay the problem is there is a two stage rocket with a payload of 200kg and isp 2943m/s. It has a total delta v of 10km/s and at each stage it produces half of the total delta v. The question is to calculate the initial mass prior to launch, I've been told also that for...
  42. F

    Rocket Experiment: Testing Thrust Using Angular Momentum Method

    Ok so What i am thinking of doing is testing the thrust of my rocket, I am thinking of doing it this way. I will have the rocket at one end of a rotating Planck and at the other end some counter balance. I will then fire the rocket of will its in the rest position, then when it is done...
  43. P

    Accelerating rocket w/ changing mass *need to finish tonight*

    Homework Statement Prove that the upward velocity of a rocket of initial mass M0, which is propelled by fuel burning at a rate of R kg/s, is given by vy = uex * ln[M0 / M(t) ] - g * t. uex is the speed of the exhaust gas relative to the rocket and M0 is the initial mass (rocket + fuel). Also...
  44. C

    Solving Relativistic Rocket Problem in Goldstein

    This is actually a problem in Goldstein. Homework Statement A rocket that ejects stuff at a speed a in its rest frame. Demonstrate that m\frac{d v}{dm} + a\left(1 - {v^2 \over c^2}\right) = 0 in which m is the invariant mass of the rocket and v is the velocity of the rocket viewed in Earth...
  45. I

    Speed of a rocket between 2 asteroids

    As part of a daring rescue attempt, the Millennium Eagle passes between a pair of twin asteroids, as shown . If the mass of the spaceship is 2.50 *10^7 kg and the mass of each asteroid is 4.49×10^11 kg A picture is shown here...
  46. G

    Water/Air Rocket Homework: Exit Velocity & Thrust vs Time

    Homework Statement I am trying to determine the exit velocity and thrust of a water rocket as a function of time. The total rocket volume is .002m^3 (2 liter coke bottle) and 1kg of water and air initially at .35MPa. Therefore the initial volume of water is .001m^3 and the volume of air is...
  47. C

    Solving for Velocity and Force in a Rocket Problem | Conservation of Momentum

    Homework Statement A small rocket of mass 1ton is moving horizontally with a velocity of 600 m/s in the x direction.The total force on the rocket is zero.10 kg of jet gas is ejected at a velocity (in the x direction) of -6000 m/s with respect to the ground.The ejection takes place over a...
  48. J

    Calculate Speed of Exhaust Gas in Rocket Propulsion

    Homework Statement A Rocket is propelled as a result of the very rapid ejection of exhaust gas from the rear of the rocket. Given that the initial mass of the rocket and fuel is 5000kg and the 4000kg of fuel is burned in accelerating the rocket to a speed of 600m/s, calculate the speed of...
  49. C

    A rocket moves upward, starting from rest.

    Homework Statement A rocket moves upward, starting from rest with an acceleration of 32.2 m/s2 for 5.84 s. It runs out of fuel at the end of the 5.84 s but does not stop. How high does it rise above the ground? Homework Equations I do not know. All equations I have tried have been...
  50. H

    [2D projectile problem]: Rocket being launched

    Homework Statement A rocket launched at 70 degrees to the horizontal has a constant net acceleration of 8m/s^2 along this direction for 6.5s and then is in free-fall. Find: (a) the maximum height; (b) the horizontal range. Homework Equations Kinematics equations (along x and y)...
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