I would say communism ☆〜（ゝ。∂）
Answer:
Explanation:
https://prezi.com/rfl2rljqy3uy/describe-the-impact-of-paper-making-woodblock-printing-compass-and-gunpowder/
Answer:
Velocity is defined as a vector measurement of the rate and direction of motion. Put simply, velocity is the speed at which something moves in one direction. The speed of a car traveling north on a major freeway and the speed a rocket launching into space can both be measured using velocity.
AND
Examples:
Revolution of Earth around the sun.
Revolution of moon around the earth.
Velocity of a satellite around the earth.
Velocity of a car while driving.
Velocity of a ball when hitted with a bat.
Velocity of water coming from a tap.
Velocity of the train .
Characteristic velocity or , or C-star is a measure of the combustion performance of a rocket engine independent of nozzle performance, and is used to compare different propellants and propulsion systems.. Formula = ˙ is the characteristic velocity (e.g. m/s, ft/s) is the chamber pressure (e.g. Pa, psi)
Air pollution is when unwanted chemicals and poisonous substances are added to air, making it harmful to most organisms such as humans, plants, animals, etc... and even the atmosphere.
By different human activities, we add a lot
of smoke and dust into the air.
The biggest cause of air pollution is the use of fossil fuels.
These are mainly coal, petrol/diesel, and natural gas.
For example, if you have been in the car before and are stuck in traffic,
you will see fumes coming out of many vehicles.
These fumes are poisonous gasses that make the air polluted.
