Page 160 - Knowledge Organiser Yr8 24-25

Knowledge Base: Science 8.15 Mechanics Year 8
3. Gas Pressure
3.1
What causes gas pressure?
When gas particles collide with each other and the walls of their container
3.2
Name two ways you can increase gas pressure
Decreasing the volume Increasing the temperature
3.3
How does decreasing the volume of a container cause an increase in gas pressure?
Decreasing the volume decreases the amount of space the particles are occupying. This results in more frequent collisions between the particles
3.4
How does increasing the temperature of a gas cause an increase in
gas pressure?
Increasing the temperature will increase the energy of the particles and they will move quicker. This results in more frequent collisions between the particles
3.5
What is atmospheric pressure?
The force exerted on a surface by the air above it as gravity pulls it to Earth
3.6
How does atmospheric pressure change as you move above sea level?
Atmospheric pressure decreases as the height above sea level increases
3.7
How does the density of air particles change as you move above sea level?
The density of air particles decreases as you move above sea level
3.8
Why is atmospheric pressure greater at the surface of the earth?
The air particles are closer together (have a higher density) and therefore there are more particles exerting a force on the surface
1. Density
1.1 What is density? A measure of how much mass there is in a set volume
1.2
Which state of matter has the greatest density and why?
Solid because the particles are close together and therefore there are lots of particles in a set volume
1.3
Which state of matter has the lowest density and why?
Gas because the particles are spread out and therefore there are very few particles in a set volume
1.4
What is the equation to calculate density?
Density = mass ÷ volume
1.5
What is the unit for density?
g/cm3
2. Pressure
2.1
When you stand on a surface why do you exert a downwards force?
Due to your weight
2.2
What is pressure?
A measure of how much force is applied over a certain area
2.3 At what angle does pressure act?
2.4 What is the equation for pressure?
2.5 What is the unit for pressure?
90o to the surface Pressure = force ÷ area N/m2
2.6
Which type of shoe will exert more pressure on the ground and why?
Figure 1: Distribution of particles above sea level
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