History of ElevatorsBy Mary Bellis (About.com)

• Primitive elevators were in use as early as the 3rd century BC, operated by human, animal, or water wheel power.

19th Century Elevators• From about the middle of the 19th century,

elevators were powered, often steam-operated, and were used for conveying materials in factories, mines, and warehouses.

In 1835, architects Frost and Stutt built the "Teagle",

a belt-driven, counter-weighted,

and steam-driven lift was developed in England.

• In 1853, American inventor Elisha Otis demonstrated a freight elevator equipped with a safety device to prevent falling in case a supporting cable should break.

• While, Elisha Graves Otis did not actually invent the first elevator, he did invent the brake used in modern elevators, and his brakes made skyscrapers a practical reality.

• Electric elevators came into to use toward the end of the 19th century. The first one was built by the German inventor Werner von Siemens in 1880.

1880 Mannheim Trade exhibition

in Germany

Modern Elevators How Stuff Works• Hydraulic elevator

• Modern Cable System

• Safety Systems

http://science.howstuffworks.com/transport/engines-equipment/elevator1.htm

http://science.howstuffworks.com/transport/engines-equipment/elevator3.htm

http://science.howstuffworks.com/transport/engines-equipment/elevator5.htm

You Weigh Less Accelerating Downward.• When standing in the elevator

before it starts. The man weighs 600N.

• When the elevator starts downward, the normal force is reduced and therefore the man’s weight is reduced.

Elevator Problems – Accelerating Downward

You Weigh Less Accelerating Upward.• When standing in the elevator

before it starts. The man weighs 600N.

• When the elevator starts upward, the normal force is reduced and therefore the man’s weight is increased.

Elevator Problems – Accelerating Upward

What if the cable snapped?

• When the elevator’s cable snapped, the man is in freefall and will eventually have no normal force and is therefore weightless --- until the inevitable!