The Science of Rockets Chapter 2, Section 1 P40-45

A History of Rockets Rocket: device that expels gas in one direction and moves in the opposite direction Rocket technology originated in China hundreds of years ago and gradually spread to other parts of the world Rockets were developed for military use and for fireworks

A History of Rockets Origins of Rockets First rockets made in China in 1100’s Arrows coated with flammable powder Lit and shot with bows Chinese used gunpowder around 1200 British greatly improved rockets in 1800’s War of 1812, Fort McHenry in Baltimore “Rocket’s red glare” British rockets used against US

A History of Rockets Development of Modern Rockets Modern rockets developed in early 1900’s Scientists involved: Tsiolkovsky – Russian Goddard – American von Braun – German

A History of Rockets Tsiolkovsky – Russian Goddard - American Described how rockets work Proposed designs for advanced rockets Goddard - American Built rockets to test his designs von Braun – German Designed V2 rocket carried explosives Major advances during WW II Brought to US after war Directed development of rockets used in US space program

How Do Rockets Work? How do rockets work A rocket moves forward when gases shooting out the back of the rocket push it in the opposite direction Similar to balloon propelled through air releasing gas Fuel is burned in most rockets produces hot gas Gas pushes outward in every direction Gases only leave out opening in back Gases moving out openings moves rocket forward

How Do Rockets Work? How do rockets work Figure 3: Action Force Hot gases pushed out of the engine Reaction Force Hot gases push rocket forward / upward

How Do Rockets Work? Action and Reaction Forces Newton’s 3rd Law of Motion: For every force, or action, there is an equal and opposite force, or reaction Balloon Air moves out of the balloon - Action Balloon moves forward – Reaction

How Do Rockets Work? Action and Reaction Forces Thrust: reaction force that propels rocket forward Depends on mass & speed of propelled gases Greater thrust – greater rocket’s velocity Velocity: speed in a given direction

How Do Rockets Work? Orbital and Escape Velocity Rocket must have more upward thrust than downward force to liftoff Orbital velocity: velocity rocket must reach to establish orbit around Earth Rockets slower than orbital velocity fall back to Earth Rockets faster than orbital velocity flies into space Escape velocity: velocity rocket must reach to fly beyond planet’s gravitational pull

How Do Rockets Work? Rocket Fuels Rockets create thrust by ejecting gas 3 types of fuel used in modern spacecraft Solid fuel Liquid fuel Electrically charged gas particles (ion)

How Do Rockets Work? Rocket Fuels Solid fuel Liquid fuel Oxygen mixed with solid, dry explosive chemical Example: firework Disadvantage: once fuel ignites it burns until gone Liquid fuel Carry liquid oxygen & liquid fuel in separate compartments Pumped into chamber and ignited Advantage: fuel burning can be controlled Electrically charged gas particles (ion) Expel gas ions Create less thrust Very fuel efficient

Multistage Rockets Idea: What if empty part of rocket could be discarded so you didn’t have to continue carrying it? Main advantage of multistage rockets: Total weight of rocket is greatly reduced as rocket rises

Multistage Rockets Total weight of rocket is greatly reduced as rocket rises Idea proposed by Tsiolkovsky in 1903 Smaller rockets (stages) stacked on larger rockets When fuel is used up, that container falls away The next rocket (stage) ignites Left with single rocket (stage) left at end

Multistage Rockets Total weight of rocket is greatly reduced as rocket rises Uses Saturn V sent spacecraft to the moon 1960’s Used to launch satellites and space probes today Multistage Rocket Active Art PHSchool.com (cfp-5021))

Homework Read Section 1, p40-45 Answer ?s 1-3 p45 AND Analyzing Data ?s 1-4 p43 or Fill out Google Form