Transcript rocket - Madison County Schools

Mav Mark
10/21/11
Of the two types of combined forces, which one is
present if the net force is ≠0.
The Science of
Rockets
Notes
A History of Rockets
• A rocket is a device that sends gas in
one direction to move the rocket in the
opposite direction. A rocket sends gas
out the back, causing the rocket to
move forward.
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A History of Rockets
In the 1860, the famous science fiction author Jules
Verne (Journey to the Center of the Earth; 20,000
Leagues Under the Sea; Around The World In 80
Days) wrote about a 600 foot cannon sending people
to the moon.
Instead of using a cannon, humans eventually used
rockets.
The first rockets were made in China in the 1100s.
These rockets were arrows that could be set on fire
and then shot with bows.
The first modern rockets were built in the early
A History of Rockets
• Inspired by the works of Jules Verne,
around the year 1900, a Russian high
school teacher by the name of
Konstantin Tsiolkovsky began to
describe in scientific terms how rockets
work and proposed designs for
advanced rockets, but he himself never
built one.
A History of Rockets
• Taking it one step farther, around 1915,
an American physicist began
constructing and testing rocket designs.
His name was Robert Goddard.
• Goddard is considered to be the father
of modern rocket science.
A History of Rockets
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World War II brought about many advances in
rocket technology, primarily by the Germans.
A German by the name of Wernher von Braun
designed the V-2 rocket, which could travel 300
km and was used to destroy many civilian and
military targets.
Towards the end of the war, von Braun and
many other German scientists defected to the
United States, bringing about 127 of the best
German minds to the American’s side.
How Do Rockets
Work?
• A rocket moves forward when gases
shooting out the back (nozzle) of the
rocket push it in the opposite direction.
• Newton’s Third Law of Motion: For
every action (gases pushing out of the
nozzle) there is an equal and opposite
reaction (the rocket is pushed
upwards).
How Do Rockets
Work?
• A rocket burns fuel inside of a
combustion chamber. When the fuel
burns, the hot expanding gases are
forced out of the nozzle at the bottom of
the rocket.
• The force of the gases shooting out of
the nozzle is called the action force.
How Do Rockets
Work?
• The gases shooting out of the nozzle
send the rocket up. The force that
moves the rocket forward is called the
reaction force.
• The reaction force that sends a rocket
forward is called thrust.
How Do Rockets
Work?
• For a rocket to leave the ground, the force of the
thrust must overcome two other forces that push
downward on the rocket, creating a net force >0.
• Weight is the force of gravity on the mass of the
rocket.
• Drag is the force of air friction that the rocket
encounters as it travels through the atmosphere.
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Rocket Velocities
The greater the thrust, the greater the
rocket’s velocity.
There are three velocities that a rocket
can achieve: suborbital, orbital, and
escape.
Suborbital velocity is any velocity high
enough to reach 100km above sea level,
but not enough to make it circle the
planet.
Suborbital velocity is anything <8km/s.
Rocket Velocities
• In order for an object to orbit, it must
reach orbital velocity.
• Anything slower than orbital velocity,
and the rocket will fall back to Earth
before completing one orbit.
• For Earth’s gravity, orbital velocity is
achieved around 7 km/s.
• This is the speed at which artificial
satellites and the International Space
Station travel.
Rocket Velocities
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If a rocket is required to leave Earth’s
gravitational field completely, then it must
move even faster. This is known as escape
velocity.
This can be achieved with a velocity
exceeding 11km/s or approximately 40,200
kilometers per hour.
All space probes to other planets and
satellites leaving out solar system must travel
at this velocity.
Rocket Fuels
•These rapid velocities require special
propellants, or fuels. There are three
primary varieties:
•Solid Fuel (like in fireworks)
•Liquid Fuel (like in the space shuttles)
•Ion Propulsion (used in modern space
probes after leaving orbit)
Multistage Rockets
• A rocket made up of several small
rockets is called a multistage rocket.
• In a multistage rocket, smaller rockets
are placed one on top of another. Each
of the smaller rockets is called a stage.
The different stages fire one after the
other.
Multistage Rockets
• When a stage runs out of fuel, the stage
drops off - making the rocket lighter and the next stage begins firing.
• At the end, there is just a single stage
left, which is the spacecraft.