💥 Energy
Energy can’t be created or destroyed — only stored, transferred, or dissipated.
This is the Law of Conservation of Energy.
⚡ Energy Stores
There are 8 main energy stores:
1️⃣ Thermal (Heat) – in all objects; increases with temperature.
2️⃣ Kinetic – in moving objects.
3️⃣ Gravitational Potential – in raised objects.
4️⃣ Elastic Potential – in stretched or compressed objects.
5️⃣ Chemical – in fuels, food, and batteries.
6️⃣ Magnetic – in magnets that attract or repel.
7️⃣ Electrostatic – between charges that attract or repel.
8️⃣ Nuclear – in atomic nuclei, released by fission or fusion.
💡 Energy can be transferred by 4 main ways:
🧪 Required Practical – Specific Heat Capacity
Aim: To measure the specific heat capacity of a material (e.g. aluminium block).
Method:
1️⃣ Measure the mass of the block.
2️⃣ Insert a heater and thermometer.
3️⃣ Record starting temperature.
4️⃣ Turn on power supply and measure current (I) and voltage (V).
5️⃣ Record temperature at intervals.
6️⃣ Calculate energy transferred using E=VItE = V I tE=VIt.
7️⃣ Plot temperature vs. energy graph → gradient gives specific heat capacity.
💪 Work Done by a Force
When a force moves an object, energy is transferred.
Formula: W=Fs
- W: work done (J)
- F: force (N)
- S: distance moved (m)
💡 1 J of work = 1 N of force moving 1 m in direction of force.
⚙️ Power (P)
Power = rate of energy transfer.
Power = work done ÷ time taken
- P: power (W)
- E: energy transferred (J)
- W: work done (J)
- t: time (s)
💡 1 watt = 1 joule per second.
🔄 Energy Transfers in a System
A system = a group of interacting objects.
Energy transfers within or between stores.
Example:
- Ball dropped → GPE → kinetic energy → sound + heat (dissipated energy).
- Dissipated energy = wasted energy, often as heat to surroundings.
🌞 Energy Resources
Renewable resources – replaced naturally:
- 🌬️ Wind – no fuel cost, unreliable
- 🌊 Tidal – predictable, expensive setup
- 🌞 Solar – free, weather dependent
- 🌋 Geothermal – reliable, location limited
- 🌊 Hydroelectric – reliable, damages habitats
- 🌾 Biofuel – renewable but uses land
Non-renewable resources – finite, release CO₂:
- 🪨 Coal, 🛢️ Oil, 🔥 Natural Gas, ⚛️ Nuclear Fuel (uranium/plutonium)
💡 Environmental impact:
- Burning fossil fuels → greenhouse gases
- Mining & drilling → ecosystem damage
- Renewables → cleaner but may affect wildlife
