P1.3 Flashcards
What is the average atmospheric pressure at sea level?
101 kPa (101,000 Pa)
A force of 10 N acts over a surface area of 2 m^2. What is the pressure?
10/2= 5 Pa
What are fluids?
Liquid and gases are fluids
Which type of shoe is best for walking on snow?
Wide shoes with a flat sole are the best as the force is spread over a larger area, which reduces pressure. Narrow shoes will not spread pressure as well.
What Greek letter is used to represent density?
p (rho)
What happens to pressure in a liquid as it’s depth increases?
Pressure increases with depth as there is an increase in weight of liquid above.
In which direction does pressure act in a liquid?
Pressure in a liquid acts in all directions as the particles are tightly packed. The weight of liquid particles increases pressure on particles below.
What is the meaning of pressure?
Force per unit area
What is the unit of pressure?
Pa
Explain why atmospheric pressure varies with height.
As the volume increases the pressure increases because there are more molecules in a given volume so there are more collisions between the gas molecules and surfaces so there is a greater force over a given area.
As you increase the height the pressure decreases
as shown by the negative gradient on the graph.
As you go higher the weight of air above is less.
Evaluate a model of the Earth’s atmosphere against real data.
In a simple model of the atmosphere the density is constant so, as in a liquid, the pressure at a horizontal layer is due to the weight of air above it. As you increase the height the pressure decreases. As you go higher the weight of air above is less.
Producing an inverse relationship as shown on the graph. The gradient of the graph would be less steep at all points/it would be shallower because the pressure at any height would be greater .
Explain the relationship between the temperature and pressure of a gas.
As the temperature increases the pressure increases because the average speed of the molecules has increased so there are more collisions between the gas molecules and surfaces so there is a greater force over a given area.
Explain how the motion of molecules can affect gas pressure.
Molecules collide with the surface producing a force acting over an area
calculate the pressure differences acting on a floating object.
calculate the pressure differences acting on a floating object.
Explain why some objects float and others sink.
Upthrust is caused by a larger pressure on the bottom of an object submerged in a liquid. The force of an object in a fluid acting on the area of the object. upthrust = weight in air – weight in water.
use ratios to draw a sketch graph and estimate values.
use ratios to draw a sketch graph and estimate values.
apply the pressure in a liquid equation to calculate depth or density.
pressure in a liquid =
height x density x acceleration due to gravity
absolute zero
the lowest temperature that is theoretically possible, equivalent to 273.15 °C
atmosphere
the layer of air, including oxygen, nitrogen, carbon dioxide, and other gases, above the Earth’s surface
atmospheric pressure
the gas pressure caused by the atmosphere due to the density of the air at that height, equal to approximately 100 kPa at the surface of the Earth
gas pressure
the pressure exerted by a gas due to the collisions of the particles in the gas with the container
inversely proportional
this is when one value increases as another value decreases in the same ratio
liquid pressure
the pressure in a liquid due to the weight of the liquid above it
pascal (Pa)
the unit of pressure; 1 Pa is equal to 1 N/m2
explain why the pressure in a liquid varies with depth and density.
explain why the pressure in a liquid varies with depth and density.
