Pressure Flashcards
How does pressure build?
> Gas particles with lots of kinetic energy collide with the walls of their container at right angles
Causes larger force on the inside of the container than on the outside so pressure builds
What would happen if a marshmallow was put inside of a vacuum, and why?
> The marshmallow would increase in size
Because the pressure on the inside of the marshmallow would be greater than the pressure on the outside (there are no air particles to collide in a vacuum)
What is the formula that links area, force and pressure?
pressure = force / area
p = F / A
What is the relationship between force and pressure?
Force is directly proportional to pressure.
What is the relationship between surface area and pressure?
Surface area is inversely proportional to pressure.
What is the formula that links density, height, gravitational field strength and Pressure?
Pressure = height x density x gravitational field strength
Remembering tip: harry potters glasses
Explain why resurfacing too quickly after diving under water can be dangerous.
Pressure on a diver changes as they return to surface. This means that the nitrogen in the bloodstream will expand and won’t escape the body through diffusion which could cause the nitrogen bubbles to block capillaries and veins in the body, preventing blood flow to vital organs.
Explain why pressure is greater as you go further underwater.
As you descend into water the weight of the water particles on top of you increases (as you go further down there is more on top of you). This causes the pressure to be greatest at the sea bed.
There is a ball submerged by 1m in water and another submerged by 5m. Which has the largest resultant force and why?
The ball at a depth of 5m has a greater resultant force because there is more force pressing down on the ball for the resultant force to counteract.
What causes atmospheric pressure?
Atmospheric pressure is caused by air particles colliding with the surface of an object. Each impact exerts a tiny force on a surface, But the number of particles that collide each second is large. 
What is the relationship between pressure and altitude?
Pressure decreases as altitude increases
Pressure is inversely proportional to altitude.
Explain how a straw works.
When you suck through a straw, you remove the air particles that fill it which causes the pressure inside of the straw to decrease. This means that the liquid then travels up the straw as there is a larger pressure on the outside of the straw.
What is a hydraulic system?
A hydraulic system is a machine that uses liquid to transmit a force.
How does a hydraulic system work?
The simplest type of hydraulic machine is made of two pistons connected by a liquid filled pipe. If one piston is pressed, the force is transmitted through the liquid filled pipe, and the other piston moves.
Why are liquids used in hydraulic systems instead of solids or gases?
The particles must be able to move however gases cannot be used as they are easily compressible so this means they are not as good at transmitting forces. Liquids can move freely but particles are close together so are incompressible. 
