# What are springs and how do they work?

WHAT ARE SPRINGS AND HOW DO THEY WORK
Springs are metal coils that close or open devices either manually or mechanically. You use many springs in your daily life but you might not even know it. There are springs in a bathroom scale, ball point pens, and even bridges. Springs can also be used to hold things in place so they won’t collapse. The webbing of a tennis racket has springs on it so when you hit the ball, it will get an extra boost to get over the net. Robert Hooke made a law about elasticity. Robert Hooke stated that restoring force = -spring constant x distortion. This equation is called Hooke’s law and states about elasticity (the more weight applied to a spring, the more it will stretch out.)
 Diagram stating different weights on the same spring (Hooke’s Law)

What we use them in
We use springs in everyday life. We use them in toys, cars, pens, bikes, and weapons. In some toys, there are springs that will make things move back in place or move to a different place. In cars, there are shocks that will absorb bumps so it won’t be rough on the driver or passengers. There are also shocks in bikes. There is springs in pens so you can retract and extent the point, and there is springs in weapons to make them fire.
 Spring scale representing Hooke’s Law of elasticity

History
Springs were used for a long time in human history. A very long time ago, early humans made bows (and arrows) to hunt. The string acts as a spring because it uses elasticity and potential energy to launch the arrow forward. There are many different types of springs that we use today. There are small springs in pens and large springs in cars and bridges. Some springs don't even look like springs. They are controlled by air or fluids to bend or extent/retract things. A good example is a bulldozer. They use gas springs to raise the shovel up and down mechanically.

Springs are commonly made of steel alloys because they are strong but flexible. The most popular is high-carbon, the same material that is used to make guitar strings, oil-tempered low-carbon, chrome silicon, chrome vanadium, and stainless steel. Other metals that are sometimes used to make springs are beryllium copper alloy, phosphor bronze, and titanium. Rubber or urethane may be used for non-coil springs. Scientists are trying to make spring out of glass fiber compost.

Demands
Springs are being highly demanded because more and more people are buying computers and cell phones. They have small springs to move different mechanisms in the device. Springs are made into the spiral or other shape when it is still in a liquid form. Then it hardens into the form and is sold. Medical devices also use small springs called micro springs. Japanese scientists designed a springs that’s coil is the same with of one strand of human hair and they are trying to make it even smaller.

Glossary
Coil: a connected series of spirals or rings into which something is wound
Shocks: absorbers in an automobile
Elasticity: the state or quality of being elastic
Potential energy: the energy of an object or a system due to the position of the body or the arrangement of the particles of the system
Alloy: a mixture ormetallic solid solution composed of two or more elements

Citations:
Bloomfield, Louis. How Everything Works. Hoboken, NJ : Wiley, c2007. Print.
Hooke, Robert: Hooke’s law of elasticity of materials. Photograph. Encyclopedia Britannica. Web. 27 Sept. 2012. <http://school.eb.com/eb/art-123664>.
Hooke’s law. Art. Encyclopedia Britannica. Web. 27 Sept. 2012. <http://school.eb.com/eb/art-153434>.

Macaulay, David. The Way Things Work. Boston Houghton Mifflin 1988. Print.

pen: ballpoint pen. Art. Encyclopedia Britannica. Web. 27 Sept. 2012. <http://school.eb.com/elementary/art-110892>.

"spring." Encyclopædia Britannica. Encyclopædia Britannica Online School Edition.Encyclopædia Britannica, Inc., 2012. Web. 27 Sept. 2012.<http://school.eb.com/eb/article-9069244>.

Picture:
http://school.eb.com/eb/art-123664/Illustration-of-Hookes-law-of-elasticity-of-materials-showing-the?&articleTypeId=1