Hobbies And Interests
Air Pressure
Suction is created when the pressure outside of the suction cup is greater than the pressure inside the cup. To create this dynamic, the cup must be sealed from the outside air to prevent stabilizing the air pressure. To explore how air pressure works, create your own suction cup with a glass filled half way with water and an index card. Wet your finger and run it around the lip of the glass to create a seal. Lay the index card on top of the glass. Flip the glass over quickly. Note that the index card does not fall off the glass under the weight of the water inside. The ambient air pressure pushes against the index card holding it on.
Adherence Ability
The difference between the pressure inside and outside the cup affects the strength of the suction. Thus, porous surfaces allow air into the cup, causing stabilization between the air inside and outside the cup. To explore this concept, press a plastic suction cup on different surfaces types. Try a desktop, a refrigerator door, a window and an easel. Apply the suction cup by pushing down and letting the suction cup stick. Note the difficulty you have in getting the cup to stick. Remove the cup from the surface. Note the difficulty of removal from each surface. Repeat the experiment a second time, but dip the suction cup in water before applying to each surface. Compare the difference in results for each surface.
Elevation Pressure
Air pressure is greater closer to the earth, where the full weight of the air meets terra firma. Likewise, air pressure is weaker the further up in elevation one climbs. Scientists have experimented with application of suction cups by climbing up the sides of tall buildings. As the explorer reaches the top, the suction of the cup is markedly less and may fail. Experiments can be conducted to compare the strength of suction on the first floor of a building compared with a higher floor.
Strength
The vacuum created within the cup can be incredibly strong. It will endure so long as the pressure outside remains greater than the pressure inside. As such, suction cups are used for many purposes to hold tools or equipment to a flat surface. Test the strength of suction in a plastic suction cup with a hook on the end. Hang items of different weights on the cup hook to see how much weight the vacuum can withstand. Another test is to secure a plastic suction cup to the refrigerator door and attempt to open the door. Compare the results against the suction created by dipping the cup into water and then adhering it to the refrigerator door again.