Pressure Flashcards
What is pressure?
Pressure is defined as the amount of force acting per unit area.
What is the SI unit of pressure?
Pascal (Pal)
Formula of pressure?
Pressure (N/m^2) = Force (N) divided by Area (m^2)
What is atmospheric pressure?
Pressure exerted by the air in the Earth’s atmosphere on surfaces.
Explain how we drink water using a straw
When the air in the straw is removed, the pressure inside the straw is lesser than the atmospheric pressure outside. Hence, the atmospheric pressure pushes the water into the straw until it reaches the same air pressure outside the straw, preventing any more liquid from entering the straw.
Explain why ice-skating athletes regularly sharpen their blades.
A thinner blade has a smaller area of contact to exert a large pressure on the ice surface. This allows the ice skater to cut deeper into the ice and have a better grip.
Explain why snow skiing uses large blades.
Larger blades have a larger area of contact with the snow, exerting a lower pressure and preventing the skier from sinking into the snow.
Explain why it would not be dangerous to lie on a bed of nails.
The total area of contact between the nails and the person would be larger, resulting in a smaller pressure acting on the object.
Explain why breathing seems to get more difficult at higher altitudes.
As the altitude increases, the atmospheric air pressure decreases. To achieve the same amount of air per breath, a person would need to breathe harder and faster.
Explain how a rubber suction cap adheres to the wall.
When the rubber suction cap hits the wall, the push force causes most of the air undermeath the cap to be squeezed out, causing the air pressure inside the suction cap to be lower than the atmospheric air pressure. The atmospheric air pressure pushes down on the suction cap, holding it firmly against the wall.
Explain how pressure is related to water depth.
The weight of the water body acting on the object in all directions increases with increasing depth, hence the pressure increases with increasing depth.
Should a water dam be constructed with uniform thickness?
No. As the pressure increases with increasing depth, the bottom of the dam will experience the greatest amount of pressure pushing against the walls. The water dam should be constructed with an increasingly thicker base, where the bottom has the thicker base to withstand the increasing water pressure.
