Pressure Flashcards
Define the term pressure.
Pressure is defined as the force, F acting normally per unit area, A. (SI unit: Pascal, Pa)
State a property of pressure acting on liquid.
The force by a static fluid on an object is always perpendicular to the surface of the object. Liquid pressure at a point is caused by the weight of liquid pressing from above.
Explain how gas pressure occurs.
The collisions of air particles against the inner surfaces of the container give rise to pressure.
The internal walls of the container experience pressure due to the particles.
Under what circumstances would the gas pressure be 0 Pa?
When there is vacuum (i.e. no air molecules) in the container.
Explain why air pressure is greater at sea level as compared to higher altitudes.
Atmospheric pressure is due to gravity, there is a higher concentration of air particles near the sea level as compared to the higher altitudes. The higher number of air particles means that there is more mass, hence higher pressure.
Explain, using concepts of pressure, how a suction cup works.
When a suction cup is sealed against a surface, air is squeezed out of the cup, creating a vacuum inside the suction cup.
As such a low pressure region is created inside the suction area. Since the atmospheric pressure outside the suction cup is greater, the atmospheric pressure presses down on the low pressure area inside the cup, that creates the suction.
