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PULL! Air is a lot stronger than you've ever imagined. Pressure bears down on everything, all the time. Witness this incredible strength first hand as you try to tug apart a rope connected only by pressure. Don't let the pressure get to you! | Go to Demonstrations |
HOW IT WORKS
There are two sides to every equation, and Air Pressure is no different. We refer to the 'normal conditions' a person is influenced by as STP: Standard Temperature and Pressure. This specific pressure is referred to as 1 atmosphere, or atm. Although there are slight deviations from this norm depending on where a person is, for most cases it can be assumed 1 atm.
It is important to remember the influence of pressure when trying to tug these two ropes apart. When the two plates are placed together and left there, essentially nothing happens. The pressure is equalized on all sides of the system. If, however, the two plates have no air between them, the pressure on either side is significantly greater than in between, causing them to stick together. And quite strongly. Such a near vacuum can be achieved easily with the devices we use. On one of the plates is an air valve, similar to what you would find on a tire. As the two plates are held to one another, the air in between them wants to escape. By opening the valve, a path is created that allows such, evacuating the air from between the two surfaces.
With no air in the middle, the 1 atm on each outer plate's side pushes it towards the negligible pressure in between the two. Areas of high pressure want to move towards areas of low pressure. With so much force pushing the two plates together, it becomes incredibly difficult to pull the two apart.
There are two sides to every equation, and Air Pressure is no different. We refer to the 'normal conditions' a person is influenced by as STP: Standard Temperature and Pressure. This specific pressure is referred to as 1 atmosphere, or atm. Although there are slight deviations from this norm depending on where a person is, for most cases it can be assumed 1 atm.
It is important to remember the influence of pressure when trying to tug these two ropes apart. When the two plates are placed together and left there, essentially nothing happens. The pressure is equalized on all sides of the system. If, however, the two plates have no air between them, the pressure on either side is significantly greater than in between, causing them to stick together. And quite strongly. Such a near vacuum can be achieved easily with the devices we use. On one of the plates is an air valve, similar to what you would find on a tire. As the two plates are held to one another, the air in between them wants to escape. By opening the valve, a path is created that allows such, evacuating the air from between the two surfaces.
With no air in the middle, the 1 atm on each outer plate's side pushes it towards the negligible pressure in between the two. Areas of high pressure want to move towards areas of low pressure. With so much force pushing the two plates together, it becomes incredibly difficult to pull the two apart.