What is Compressed: Definition and 319 Discussions

Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches and others, as well as to atomize paint, to operate air cylinders for automation, and can also be used to propel vehicles. Brakes applied by compressed air made large railway trains safer and more efficient to operate. Compressed air brakes are also found on large highway vehicles.
Compressed air is used as a breathing gas by underwater divers. It may be carried by the diver in a high pressure diving cylinder, or supplied from the surface at lower pressure through an air line or diver's umbilical. Similar arrangements are used in breathing apparatus used by firefighters, mine rescue workers and industrial workers in hazardous atmospheres.
In Europe, 10 percent of all industrial electricity consumption is to produce compressed air—amounting to 80 terawatt hours consumption per year.

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  1. T

    Colliding blocks attached to a spring - How is the spring compressed

    "A block of mass m1 = 2.4 kg slides along a frictionless table with a speed of 10 m/s. Directly in front of it, and moving in the same direction, is a block of mass m2 = 4.6 kg moving at 2.8 m/s. A massless spring with spring constant k = 1160 N/m is attached to the near side of m2, as shown in...
  2. B

    Two Compressed Springs -> Unstable Equilibrium

    I will make a crude visualization of this system: |-------------O--------------| <-----a------><------a------> Identical springs: k1=k2=k Natural Length: l > a The problem is to prove that the system is unstable. Obviously, a slight movement directed off the horizontal axis will cause the...
  3. G

    Compressed spring and Hooke's law

    A compressed spring that obeys Hooke's law has a potential energy of 18 J . If the spring constant of the spring is 400 N/m, find the distance by which the sping is compressed. Please correct me if I am wrong, I'm not sure how find the distace. My work: k 400 N/m x=18J = 400 N/m/18...
  4. S

    Compressed Spring & Acid: E.P.E Impact & Reasons Explained

    a compressed spring is completely dissolved in acid what will happen to the elastic potential energy of the spring? With reasons. I think that the E.P.E will have an effect on the heat released but I still don't have backup. I am still not so advanced.
  5. Pengwuino

    Compressed Air Can Mystery: What's Going On?

    I was wondering something. I have this can of compressed air and when its upright and used, it fires out a bunch of air. If i turn it onto its side where the nozzle points up however, half the time the air is actually visible! (or too cold?). What is causing this? It also does it when you turn...
  6. K

    Compressed reversibly and adiabatically problem

    hey, i was wondering if anyone could help with this question. it seems simple but i can't find a formula for it. 2.5 mol of perfect gas at 220 K and 200 kPa is compressed reversibly and adiabatically until the temperature reaches 255 K. Given that its molar constant-volume heat capacity, CV,m...
  7. B

    Does a Compressed Vertical Spring Only Store Elastic Potential Energy?

    if a vertical spring is being compressed down, is the Elastic potential energy the only energy? Ee = .5kx^2 is gravity included in that? or does it not play a role? and how could I tell how far an object would fly up in the air once the spring is released? thanks
  8. S

    Helium gas is compressed form 1 atm and 25 degree C

    Helium gas is compressed form 1 atm and 25 degree C to a pressure of 10atm adiabatically. the lowest temp. of helium after compression is i don't know how to start if anyone can give me hint to start the problem it would be a great things thank you waiting for your answer i got the...
  9. R

    Recovering pressure-volume energy from compressed hydrogen?

    The energy density usually given for hydrogen is 142 MJ/kg, by which comparison is made to how much hydrogen would have to be carried for it to be competitive with gasoline-fueled vehicles: Bottling the hydrogen genie. "One kilogram of hydrogen provides about the same chemical energy (142...
  10. C

    How Does Compressing a Spring Store and Release Energy?

    I was trying to work on this for a little but couldn't figure it out. A. A spring with a spring constant k=30 N/m is compressed and latched at 0.10 m. How much elastic potential energy is stored in the spring? ? 0.15 J B. An object with a mass of 5.0 kg is placed next to the...
  11. U

    Compressed Air Car: Moving 70kg Person w/ 135 PSI Tank

    I'm building a compressed air car that will move a 70 kg person and I'm wondering how far it can go off a 135 PSI tank with 10 gallons. The vehicle should have a mass of at most 80 kg and I'm trying to figure out how to do calculations with a coefficent of friction of 0.5. Can anyone help me...
  12. J

    Water content in compressed air

    Hi- A recently installed natural gas main is showing evidence of water infiltration. Water is getting into the customers regulator and meter and freezing. The gas main was cleaned and "pigged" after the installation. The system is currently operating at an MAOP of 60 PSIG natural gas. When...
  13. B

    What is the speed of the block in this compressed spring problem?

    I have a problem that I just can't seem to figure out. Here's the problem: The drawing (Click Here) shows a block (m = 1.6 kg) and a spring (k = 325 N/m) on a frictionless incline. The spring is compressed by x_o = 0.35 m relative to it's unstrained position at x = 0 m and then released. What...
  14. P

    Interesting new concept car-runs on compressed air

    Interesting new concept car-runs on compressed "air" link here : http://www.theaircar.com/ thoughts ?
  15. D

    Compressed Air n' Pressure Question

    Does anyone know of an internet site that discusses the properties of compressed air in a tank, and how the air behaves when it is released from the tank. Also, is there an equation which describes the rate at which air leaves through a valve of a tank? Thanks much
  16. Ivan Seeking

    MDI's Compressed Air Technology Systems: C.A.T's ©(*).

    http://www.theaircar.com/howitworks.html also: http://auto.howstuffworks.com/air-car1.htm I haven't studied this yet but to me this seems an unlikely technology. This must be terribly inefficient. It even strikes me a bit as a scam - clean technology? Comments?
  17. D

    What happens to moisture when air compressed?

    On an automotive forum, a member made a statement that compressed air won't hold as much moisture as ambient pressure air because the water is "squeezed" out by the pressure and is also, therefore, "drier" air. He pointed to the need to drain water from the tank as proof of the squeezing...
  18. Y

    What is the Radius of a Black Hole If Earth Were Compressed?

    Black Holes Gre.67 67. A black hole is an object whose gravitational field is so strong that even light cannot escape. To what approximate radius would Earth (mass = 5.98 x 10^24 kilograms) have to be compressed in order to become a black hole? a. 1 nm b. 1 microm c. 1 cm d. 100 m e...
  19. brum

    Cars powered by compressed air

    http://auto.howstuffworks.com/air-car.htm
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