| Liquids and gases are fluids. | Fluids |
| What states of matter are considered fluids? | Liquids and gases. |
| Molecules or particles can move around freely in fluids. | Particle Movement in Fluids |
| How do molecules or particles behave in fluids? | They can move around freely. |
| Solids are not fluids. | Solids as Fluids |
| Are solids considered fluids? | No, solids are not fluids. |
| The particles in solids can only vibrate around a fixed position. | Particle Movement in Solids |
| How do particles in solids behave? | They can only vibrate around a fixed position. |
| Fluids exert forces on objects they touch. | Fluid Force on Objects |
| What happens when an object is placed in a fluid? | The fluid's particles constantly collide with it, exerting a force on the object. |
| The force is normal (at right angles) to any surface touching the fluid. | Direction of Fluid Force |
| In which direction does the fluid exert force on an object? | The force is normal (at right angles) to any surface touching the fluid. |
| The force acts over the area of the surface, creating pressure. | Pressure Creation |
| How does fluid force create pressure? | The force acts over the area of the surface, creating pressure. |
| You can calculate the pressure at the surface using this equation: | Pressure Calculation |
| The smaller the area, the greater the pressure will be for the same force. | Area and Pressure Relationship |
| How does the area affect pressure for the same force? | The smaller the area, the greater the pressure. |
| Snow-shoes spread the force of your weight over a bigger area. | Snow-shoes Example |
| Why do snow-shoes prevent sinking into the snow? | They spread the force of your weight over a bigger area, reducing the pressure on the snow. |
| Air pressure is all around us. | Air Pressure |
| What is the thin layer of air surrounding the Earth called? | The atmosphere. |
| When air molecules hit different surfaces, they exert a force that creates atmospheric pressure. | Atmospheric Pressure |
| What creates atmospheric pressure? | Air molecules hitting different surfaces and exerting a force. |
| The number of air molecules (and the weight of the air) decreases with height above the Earth's surface. | Altitude and Air Molecules |
| How does the number of air molecules change with height above the Earth's surface? | The number of air molecules decreases with height. |
| The atmosphere is less dense at higher altitudes. | Density of Atmosphere |
| What happens to the density of the atmosphere at higher altitudes? | The atmosphere becomes less dense. |
| Fewer air molecules mean fewer collisions. | Air Molecules at High Altitudes |
| How does the number of collisions between air molecules change at higher altitudes? | There are fewer collisions at higher altitudes. |
| Atmospheric pressure decreases with increasing altitude. | Atmospheric Pressure and Altitude |
| What happens to atmospheric pressure as altitude increases? | Atmospheric pressure decreases. |
| Atmospheric pressure also exerts a downwards force on other fluids. | Downwards Force of Atmospheric Pressure |
| What causes pressure at any point in a fluid? | The pressure is caused by both the fluid and the atmosphere above it. |
| Someone swimming underwater experiences pressure due to the weight of the atmosphere and the weight of the water above them. | Swimming Underwater Pressure |
| Why does someone swimming underwater experience pressure? | They experience pressure due to the weight of the atmosphere and the water above them. |
| Water is over 800 times denser than air. | Density of Water vs. Air |
| How much denser is water compared to air? | Water is over 800 times denser than air. |
| The contribution to the overall pressure from the water is much bigger than that from the atmosphere. | Contribution to Overall Pressure |
| Which contributes more to the overall pressure underwater: the water or the atmosphere? | The contribution from the water is much bigger than that from the atmosphere. |
