Lesson 2:Heat Transfer/ Conduction Flashcards
What is the difference between “heat” and “temperature?”
- Heat: Thermal energy stored in all objects.
- Temperature - Average kinetic energy of molecules
What is “heat” measured in?
- Heat = Thermal energy
- Heat measured in Joules (J)
What is the standard unit for temperature?
- Kelvins (K)
Why is temperature the measure of average kinetic energy of particles?
- This is because when you heat something, particles move quicker.
What does thermal energy depend on?
- Thermal energy depends on the number of particles.
pot of tea has more thermal energy than cup of tea
What is an “insulator”?
- An insulator is a material that doesn’t conduct well.
What are the 2 types of conduction?
- Thermal conduction
- Electrical conduction
Why are metals good conductors of heat and electricity?
- They have delocalised electrons that can transfer thermal energy through the material.
Why are some metals better conductors than others?
- Some metals have more delocalised electrons than others.
Why does wood feel warmer than metal when they are both at the same temperature?
- The wood is an insulator of your body’s heat.
- The metal is a conductor of your body’s heat.
- So makes it feel cold*
What is meant by “direction of heat transfer?”
- This means that heat is always transferred from a hot area to a cold area.
What is the direction of heat transfer for foods in the fridge?
- The food has thermal energy.
- This is transferred to the cold fridge.
- This makes food cold, preserving it.
What is meant by thermal equillibrium?
- Thermal equillibrium means an object isn’t gaining or losing thermal energy.
What is room temperature?
- Around 27 degrees celcius.
What is the direction of heat transfer for a 46 degree cup of tea?
- The hot tea transfers energy to the surroundings.
What is the direction of heat transfer for ice to melt?
- The warmer surroundings transfer energy to the 0 degree ice cube.
Why does ice melt faster on a metal to wood?
- The materials transfer heat from surroundings to ice by conduction.
- Metal is a better conductor so transfers energy quicker.
The higher the thermal conductivity of a material the higher the………………………….
- Energy transferred by conduction across the material.
What 2 factors affect the rate of cooling down of a building?
ie. amount of thermal energy that is lost
- Thermal conductivity of walls.
- Thickness of the walls.
How does heat escape from walls?
- Cavity in between 2 walls.
- To reduce, fill with low conductivity foam material (insulation.)
How can we reduce heat that escapes through windows?
- Use double - glazing
- Has a lower thermal conductivity.
What can you do to reduce the rate of thermal energy transfer in walls other than using low conductivity materials?
- Use thicker walls to reduce rate of thermal energy transfer.
