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UPPCS Physics Gap Sheet: Heat and Everyday Cooling.
UPPCS has asked 21 of these. 11 have not been asked yet. Lock the first list, then read the second: it holds what UPPCS has not used yet.
First, the concept
Heat flows from a hotter body to a colder one. Temperature is not the amount of heat stored. Conduction transfers energy through matter, convection uses bulk fluid motion, and radiation can travel through vacuum.
A phase change can absorb or release heat without changing temperature. Evaporation cools the remaining liquid. Pressure changes boiling temperature, while water has unusual expansion between 0°C and 4°C.
✅ Already asked (21)
Heat transfer
- Convection · Heating drives bulk motion in liquids and gases; solids do not transfer heat by bulk convection.
- Sun's heat · Radiation carries solar energy across the vacuum of space.
- Thermos flask · Vacuum reduces conduction and convection; reflective surfaces reduce radiation.
- White summer clothing · Usually absorbs less sunlight than dark clothing under comparable conditions.
- Cloudy nights · Clouds emit infrared towards the surface and reduce net cooling.
- Woollen clothing · Trapped air slows heat transfer from the body.
- Vehicle radiator · Transfers engine heat from coolant to surrounding air.
Phase change and pressure
- Melting ice cools a drink · Ice absorbs latent heat from the drink.
- Pressure cooker · Higher pressure raises water's boiling point and speeds cooking.
- Boiling on mountains · Lower atmospheric pressure lowers the boiling point of water.
- Water freezing · Water expands on freezing; a full sealed bottle can break.
- Water from 0°C to 4°C · It contracts on heating in this interval.
- Equal temperature readings · Celsius and Fahrenheit readings coincide at −40 degrees.
- Thermal expansion of pendulum · A longer pendulum has a longer period, so expansion can make its clock slow.
Cooling and control
- Sweat and humidity · High humidity slows evaporation of sweat and reduces cooling.
- Fan cooling · Moving air speeds evaporation and heat loss from skin.
- Desert cooler · Evaporative cooling works better in dry air and adds moisture.
- Air conditioner · Transfers heat outside and commonly removes moisture by condensation.
- Open refrigerator · The room gains the electrical energy used by the running refrigerator as net heat.
- Thermostat · Automatically controls temperature, often by switching a circuit.
Thermodynamic rules
- Carburettor · Mixes air and fuel in older petrol engines; modern petrol engines commonly use fuel injection.
❌ Not asked yet (11)
🔒 11 items not asked yet
Heat transfer: 1 · Phase change and pressure: 1 · Cooling and control: 2 · Thermodynamic rules: 7
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⚠️ A fan mainly cools people through evaporation and convection. A refrigerator with its door open adds net heat to the room.
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