The simplest way to explain how a vacuum cleaner can suck up debris is to think of it like a straw. When you take a sip of drink through a straw, the action of sucking creates a negative air pressure inside the straw. A negative air pressure is lower than the pressure of the surrounding atmosphere.
A vacuum cleaner uses an electric motor that spins a fan and creates a region of low pressure inside its pipe, and the outside air pushes dust and dirt into the pipe.
Electric motors are one of the most fascinating inventions of the twentieth century. They leverage the power of induction to create motion from electricity.
Electromagnetism is one of the most important forces that we know of in physics. You may be familiar with magnets and electricity, but did you know that one can generate the other? You can use magnets to induce an electric field by causing electrons to move around, and when electricity flows, a magnetic field is created around it! This principle is used to create electric motors.
Modern aircraft and cars use hydraulics to operate brakes and steering mechanisms. Robotic systems in factories and large earth-moving equipment at construction sites also use hydraulics. The fluid is almost always an oil of some sort. Thin oil is better than water because it will not freeze or cause rusting and it keeps the moving parts well oiled.
Early peoples learned how to use flowing water to do work. Water was used to power water mills and to provide irrigation for farming. Later, people were able to use liquids to do even more after scientists learned that all liquids follow certain rules. They learned that pressure in a liquid is transmitted equally in all directions. That is, when one pushes down on the liquid in a tube the liquid will push against whatever it comes up against, even if it is bigger than the original tube. Therefore, it is possible to use a small amount of force to create a larger force somewhere else.
An elevator or lift is a vertical transport vehicle that efficiently moves people or goods between floors of a building. They are generally powered by electric motors that either drive traction cables and counterweight systems, or pump hydraulic fluid to raise a cylindrical piston.
The first reference to an elevator is in the works of the Roman architect Vitruvius, who reported that Archimedes built his first elevator, probably in 236 B.C. In the 17th century the prototypes of elevators were located in the palace buildings of England and France.
In 1852, Elisha Otis introduced the safety elevator, which prevented the fall of the cab if the cable broke.
The first electric elevator was constructed by the German engineer Werner von Siemens in 1880.
