🧪 Matter
Matter is everything that has weight (mass) and takes up space (volume).
The three states of matter:
- Solid — ice, wood, rock, metal
- Liquid — water, juice, oil, milk
- Gas — air, steam, helium, oxygen
Remember SLG: Solid, Liquid, Gas!
⚖️ Mass
Mass is the amount of matter in an object.
Units: kilograms (kg) and grams (g)
Conversion: 1 kg = 1000 g
Measured using: scales (traditional balance and digital scales)
How to measure the mass of a solid:
Place the object on the scales and read the value.
How to measure the mass of a liquid:
Weigh the empty container, add the liquid and weigh again, subtract the container mass from the total.
📝 Worked Example: Find the mass of water in a jug
- Empty jug = 200 g
- Jug + water = 750 g
- Mass of water = 750 − 200 = 550 g
📐 Volume
Volume is the amount of space an object occupies.
Units: cubic metres (m³), cubic centimetres (cm³), litres (L), millilitres (mL)
Conversions: 1 m³ = 1000 L | 1 cm³ = 1 mL
Measured using: a measuring cylinder
How to measure the volume of a liquid:
Pour the liquid into the measuring cylinder and read the scale.
How to measure the volume of a solid (displacement method):
Pour liquid into the cylinder, read the volume, add the solid, read the new volume, subtract the first reading from the second.
📝 Worked Example: Find the volume of a stone using displacement
- Water level before = 50 mL
- Water level after adding stone = 73 mL
- Volume of stone = 73 − 50 = 23 mL (= 23 cm³)
🔬 Density
Density is a measurement of the amount of matter contained in a certain volume.
Formula: density = mass ÷ volume (d = m/v)
Units: g/cm³
Steps to calculate density:
- 1. Weigh the object to find its mass
- 2. Calculate the volume using a measuring cylinder
- 3. Divide mass by volume
🔺 The Density Triangle
d = m ÷ v | m = d × v | v = m ÷ d
📝 Worked Example 1
A rock has mass 120 g and volume 40 cm³. Find its density.
📝 Worked Example 2
A liquid has mass 80 g and volume 100 cm³. Find its density.
💨 Air
Air is a mixture of gases surrounding the Earth.
- No definite shape
- Has mass and volume
- Changes volume with temperature (expands when heated)
- Can move (wind)
-
🫁 Respiration
Oxygen for living things to breathe
-
🌱 Photosynthesis
CO₂ for plants to make food
-
🔥 Combustion
Oxygen needed for burning
-
🌦️ Weather
Air movement creates weather phenomena
-
🔊 Sound
Sound travels through air
-
✈️ Flight
Birds and planes use air to fly
-
💨 Energy
Wind power generates electricity
-
🏎️ Friction
Aerodynamic shapes reduce air resistance