Page 7 - Curriculum Visions Dynamic Book

Now think about a rocket firework. A rocket of this kind is like a powered arrow. It is designed like a shaft so that it will meet as little air resistance as possible. But it is not shot by a bow; it has its own propellant (fuel) on board. Although this means that it no longer depends on an external propulsion system and can go much farther, the disadvantage is that it cannot be as slim or light as an arrow.
To keep down the air resistance created by its larger size, the rocket has a nose cone. That pushes the air aside and around the rocket’s sides, and is an example of aerodynamic styling.
The propellant inside the body of a rocket firework is a solid mixture of chemicals (called solid fuel) that is a version of gunpowder. This chemical mixture (72% nitrate, 24% carbon, and 4% sulfur) is adapted so that it will burn fiercely but not so fast that it explodes.
When the blue fuse is lit, the solid gunpowder changes into a gas, expanding and causing an increase in gas pressure. The strong casing keeps these gases from escaping anywhere but from the bottom.
As the gases rush out of the bottom of the firework, an equal and opposite reaction is produced that lifts the firework off the ground. This is called a reaction motor (see also pages 12–13). Similarly, as the gases flow out of the end of a space rocket, they cause the rocket to move in the opposite direction. This follows Newton’s laws of motion, which say that “For every action there is an equal and opposite reaction.” The “action” does not need anything to push against to cause the reaction. That is why rockets move in space where there is no air.
The explosive nature of a firework propellant makes it accelerate very quickly and keep accelerating
until it has used up all the propellant. But there is no way of closely controlling the rate at which the fuel
accelerate To gain speed. aerodynamic A shape offering as little
resistance to the air as possible.
air resistance The frictional drag that an object creates as it moves rapidly through the air.
apollo The program developed in the United States by NASA to get people to the Moon’s surface and back safely.
gravity The force of attraction between bodies.
laws of motion Formulated by Sir Isaac Newton, they describe the forces that act on a moving object.
payload The spacecraft that is carried into space by a launcher.
pressure The force per unit area.
propellant A gas, liquid, or solid that can be expelled rapidly from the end of an object in order to give it motion.
reaction An opposition to a force.
thrust A very strong and continued pressure.
voyager A pair of U.S. space probes designed to provide detailed information about the outer regions of the solar system.
Aerodynamic nose cone shape
Payload of coloured chemicals
Shaft
Propellant
 The components of a firework rocket.
is burned or guiding the rocket accurately. When the rocket has used up all of its propellant, it falls back to the ground and usually breaks up.
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