Science Y8: 8I (Fluids) Physics

Fluids

Fluids are liquids or gases.

Particle Model

The particle model explains the properties of solids, liquids, and gases.

Solids

Fixed volume, fixed shape.

Liquids

Fixed volume, takes shape of container.

Gases

Expand to fill container, take shape of container.

Particle Arrangement in Solids

Close together, held by strong forces, fixed positions.

Particle Arrangement in Liquids

Close together, held by fairly strong forces, can move.

Particle Arrangement in Gases

Far apart, held by weak forces, can move freely.

Density

Mass per unit volume of a substance.

Density Formula

Density = mass ÷ volume.

Density Units

g/cm³ or kg/m³.

States of Matter

Solid, liquid, gas.

Melting

A solid turns into a liquid.

Freezing

A liquid turns into a solid.

Evaporation/Boiling

A liquid turns into a gas.

Condensation

A gas turns into a liquid.

Sublimation

A solid turns directly into a gas.

Melting/Freezing Point

Occurs at the same temperature for a substance.

Temperature During Melting

Stays constant even if heating continues.

Temperature During Boiling

Stays constant while changing from liquid to gas.

Effect of Heating on Density

Expands, density decreases.

Effect of Cooling on Density

Contracts, density increases.

Ice Density

Ice is less dense than liquid water and floats.

Fluid Pressure Direction

Acts in all directions due to particle movement.

Increasing Gas Pressure

Add particles, heat gas, reduce volume.

Pressure in Deeper Water

Increases due to more water pressing down.

Air Pressure at High Altitude

Decreases as there is less air pressing down.

Floating & Sinking Rule

If an object's density is less than the fluid's density, it will float.

Drag

Resistance caused by air or water.

Reducing Drag

Use a smooth surface and streamlined shape.