Density & heat transfer

What is thermal energy transfer?

Thermal energy moves from hot to cold areas, such as a hot cup of tea giving out thermal energy to its surroundings.

How does the temperature difference affect thermal energy transfer?

A greater difference in temperature results in more thermal energy being transferred.

What is double glazing and how does it work?

Double glazing consists of two sheets of glass separated by a gap filled with argon or a partial vacuum, reducing heat loss through convection.

What is draught proofing and its purpose?

Draught proofing involves sealing gaps around doors and windows to reduce heat loss through conduction and convection.

What is loft insulation and its material?

Loft insulation typically uses mineral wool placed between the rafters to reduce heat loss through conduction.

What is conduction and where does it occur?

Conduction is the flow of thermal energy through an object, occurring primarily in solids.

What are good conductors of heat?

Good conductors include metals like copper.

What are insulators and give an example?

Insulators are materials that trap air and reduce heat loss, such as wool in a jumper.

What is convection and how does it work in liquids and gases?

Convection is the flow of heat in liquids and gases, where heated particles move up and cooler particles move down.

What happens to gas or liquid when it is heated?

The particles speed up, causing the gas or liquid to expand and decrease in density, allowing it to rise.

What is cavity wall insulation?

Cavity wall insulation involves filling the space between inner and outer walls with foam or insulation board to reduce heat loss.

How does thermal radiation work?

Hot objects emit thermal radiation, with higher temperatures resulting in more emitted radiation.

What materials are good at reflecting thermal radiation?

Shiny materials, such as aluminum foil, are good at reflecting thermal radiation.

What is the significance of black surfaces in thermal radiation?

Matt black surfaces are good at absorbing and emitting thermal radiation, causing objects like black cars to heat up more in the sun.

What is the formula for calculating density?

Density = Mass / Volume.

How do you calculate the density of a solid?

Measure the mass and volume of the solid, then use the formula Density = Mass / Volume.

What is the process for measuring the density of a liquid?

Measure the mass of an empty cylinder, fill it with liquid to a specific volume, and then calculate the density using the mass of the liquid.

What is the Sankey diagram used for?

A Sankey diagram visually represents energy input and output, showing useful and wasted energy.

What is the efficiency formula?

Efficiency = (Useful energy output / Total energy input) x 100.

What is the impact of insulation on energy costs?

Good insulation reduces thermal energy loss and carbon dioxide emissions, leading to lower energy costs.

What percentage of heat loss occurs through windows and doors?

Up to 25% of heat loss can occur through windows and doors.

What is the role of air in insulation?

Air trapped in insulating materials reduces heat loss through convection.

What is the significance of fossil fuels in energy consumption?

Fossil fuels emit CO₂ when burned, contributing to global warming and are finite resources.

What is the relationship between temperature difference and energy costs?

A greater temperature difference between inside and outside increases energy costs for heating.