Physic Presentation Term3v2

8/3/2019 Physic Presentation Term3v2

1/23


2/23

A rocket is a missile, spacecraft, aircraft orother vehicle which obtain thrust from a rocketengine.

The exhaust is formed from propellants carriedwithin the rocket before use in all rockets.

Rocket engines push rockets forwards bythrowing their exhaust backwards extremelyfast.


3/23

Principle of Newton's third law

The expansion of nozzles on a high pressure fluid and the rocketengines combustion accelerate the fluid to high speed andexerts a large reactive thrust on the rocket which propels therocket forwards.

The pressures acting on the combustion chamber and nozzlecause reactive thrust.

In a closed chamber, the pressures are equal in each directionand no acceleration occurs.

The remaining pressures give a resultant thrust on the sideopposite the opening, and these pressures are what push therocket along. Using a nozzle gives more force also since theexhaust also presses on it as it expands outwards doubling thetotal force.

Theory


4/23


5/23

Conservation of momentum

Since a rocket, propellant and exhaust in flight, without anyexternal, may be considered as a closed system, the totalmomentum is always constant. .

As the remaining propellant decreases, rocket vehicles become

lighter and their acceleration tends to increase until thepropellant is exhausted. This means that much of the speedchange occurs towards the end of the burn when the vehicle ismuch lighter.


6/23


7/23

Flying rockets are primarily

affected by the following:

Thrust from the engine(s) Gravity from celestial

bodies

Drag if moving inatmosphere

Lift; usually relatively

small effect except

for rocket-poweredaircraft


8/23

The first use of true rocketsDate : 1232

Who : Chinese and the Mongols

Event : War between Chinese and the Mongols the Chinese created "arrows of flying fire."

a simple form of a solid-propellant rocket.

A tube, capped at one end, contained gunpowder. The otherend was left open and the tube was attached to a long stick.

The stick acted as a simple guidance system that kept the

rocket headed in one general direction as it flew through the

air.

History


9/23

Until..

In 1898,

Konstantin Tsiolkovsky, a Russian schoolteacher

proposed the idea of space exploration by rocket.

suggested the use of liquid propellants for rockets inorder to achieve greater range

Tsiolkovsky has been called the father of modern astronautics.

When?

Who?

What?

How?


10/23

Structure Usually plastic,reduces drag

Usually aparachute orstreamer, slowsrocket downduring descent

Flameproof, tissue-likesubstance that preventsrecovery device frombeing scorched byejection charge

Prevents motor frombeing forced intorocket

Stabilizes rocket during flight

Primary function is topropel the rocket

Attaches nose cone to bodytube, takes the shock ofrecovery device ejection


11/23

MilitaryScience and research

Rescue

Space flight

Entertainment

Uses of rocket


12/23

A rocket and its payloadtogether are generallyreferred to as a missile

when the weapon has aguidance system or as arocket if it is unguided.

Examples : Anti-tank and anti-aircraft

missiles use rocket engines toengage targets at high speed at arange of several miles

Intercontinental ballisticmissiles can be used to delivermultiple nuclear warheadsthousands of miles

Anti-ballistic missiles try to stopthem.


13/23

Sounding rockets are

commonly used to carryinstruments that take

readings from 50

kilometres (31 mi) to 1,500

kilometres (930 mi) above

the surface of the Earth,

the altitudes between

those reachable by

weather balloons and

satellites.


14/23

Multi stage rocket Solid rocket


15/23

Unload the unnecessary parts during flight

Different motor for different situation

Advantages of Multi stage rocket


16/23

Lower specific impulsion

Shut down of rocket

More complex and harder to build

Disadvantages of Solid rocket


17/23

Impacts to Environment & Society


18/23

Affect the depletion of stratospheric ozone

Impact 1

Emit reactivegases that causeozone moleculesto break apart

Dischargemicroscopic particlesof soot andaluminium oxide,

which may increasethe rate at whichthose gases wreak

havoc


19/23

Global climate change

Impact 2

The exhaust from space-ship engines does addseveral kilotons of carbon

dioxide to the atmosphereevery year.


20/23

Change the radiation balance in the atmosphere

Impact 3

aluminium oxide, for example, reflect the visiblelight from the sun back into space, which cools theEarth.

those particles can also absorb infrared radiationemanating from the planet's surface, essentiallytrapping heat the way a greenhouse gas does.

These may also increase rates of skin cancer andcataracts.


21/23


22/23

Perchlorate impairs the proper functioning of thyroidgland

Improper regulation of thyroid function is the leadingknown cause of neurological impairment world wide.

At higher level of exposure, perchlorate causes thyroidcancer and harm the immune system.

Impact 4


23/23

Documents

Physic Presentation Term3v2