MASS AND WEIGHT
The mass of an object is a measure of how much matter it consists of. Mass is the same everywhere. The weight of an object is the result of the force of gravity acting on the object’s mass. Gravity (and therefore weight) decrease with distance from Earth.
THRUST AND ACCELERATION
A launcher needs sufficient thrust to lift its own mass and to overcome gravity. As fuel burns during the ascent, mass is reduced. With increased distance from Earth, both mass and the pull of gravity lessen, and the rocket picks up speed and accelerates to space.
ACTION AND REACTION
The thrust that lifts the launcher comes from burning fuel in its combustion chamber. If the chamber were sealed, it would explode. Gases are allowed to escape through a nozzle. Because they cannot escape upwards, the gases exert an upward force (reaction) that is equal and opposite to the force (action) of the escaping exhaust.
SATELLITE PAYLOAD
The cargo a launcher carries is known as a payload. All the fierce combustion and powerful forces are harnessed to lift a few tones of payload from the Earth’s Surface. Some launchers carry a heavier payload to space than others.
ESCAPING GRAVITY
At an altitude of 200km, a launch vehicle must give a satellite enough horizontal force to reach 7.8km/s, if it is to enter orbit. If it reached a little over 11km/s, the satellite would escape Earth’s gravity, and head off into space. This speed is called escape velocity.
ORBITAL PHYSICS
Imagine a bullet fired horizontally from a gun. Gravity pulls it vertically towards the Earth. If a bullet could be fired with sufficient horizontal force, it would never reach the ground: the bullet would be in the orbit. In the same way, launch vehicles carry satellites above the atmosphere and release them with enough horizontal force to remain in orbit.
The mass of an object is a measure of how much matter it consists of. Mass is the same everywhere. The weight of an object is the result of the force of gravity acting on the object’s mass. Gravity (and therefore weight) decrease with distance from Earth.
THRUST AND ACCELERATION
A launcher needs sufficient thrust to lift its own mass and to overcome gravity. As fuel burns during the ascent, mass is reduced. With increased distance from Earth, both mass and the pull of gravity lessen, and the rocket picks up speed and accelerates to space.
ACTION AND REACTION
The thrust that lifts the launcher comes from burning fuel in its combustion chamber. If the chamber were sealed, it would explode. Gases are allowed to escape through a nozzle. Because they cannot escape upwards, the gases exert an upward force (reaction) that is equal and opposite to the force (action) of the escaping exhaust.
SATELLITE PAYLOAD
The cargo a launcher carries is known as a payload. All the fierce combustion and powerful forces are harnessed to lift a few tones of payload from the Earth’s Surface. Some launchers carry a heavier payload to space than others.
ESCAPING GRAVITY
At an altitude of 200km, a launch vehicle must give a satellite enough horizontal force to reach 7.8km/s, if it is to enter orbit. If it reached a little over 11km/s, the satellite would escape Earth’s gravity, and head off into space. This speed is called escape velocity.
ORBITAL PHYSICS
Imagine a bullet fired horizontally from a gun. Gravity pulls it vertically towards the Earth. If a bullet could be fired with sufficient horizontal force, it would never reach the ground: the bullet would be in the orbit. In the same way, launch vehicles carry satellites above the atmosphere and release them with enough horizontal force to remain in orbit.
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