physics 2 Flashcards
(14 cards)
What does a material’s thermal conductivity
tell you?
how well it conducts heat
Which materials have low thermal conductivity?
thermal insulators
Give three factors that determine the rate of thermal energy transfer through a material.
- thermal conductivity of material
- temperature difference
- thickness of material
What factors affect the rate of heat loss from a building?
- thickness of walls and roof
- thermal conductivity of walls and roof
- the temperature difference between the two sides of the wall/roof
Define specific heat capacity
amount of energy needed to raise the temperature of 1 kg of a material by 1 °C
What is infrared radiation?
type of electromagnetic radiation
What is the relationship between the temperature of an object and its emission of infrared radiation?
the higher the temperature of an object, the more infrared radiation emitted in a given time
What can you tell about an object that absorbs and emits infrared radiation at the same rate?
it is at a constant temperature
Compare the amount of infrared radiation emitted and absorbed by an object that is increasing in temperature.
more infrared radiation absorbed than emitted
What is a black body?
An object that absorbs all of the radiation incident on it and does not reflect or transmit any radiation.
Name three greenhouse gases.
- water vapour
- carbon dioxide
- methane
What human activities increase the levels of greenhouse gases released?
(for example) deforestation, burning fossil fuels,
livestock farming
Why do greenhouse gases increase the Earth’s
temperature?
Earth’s surface absorbs and re‑emits radiation from the Sun, which greenhouse gases then absorb – they re‑emit this radiation back towards Earth’s surface
To determine the specific heat capacity of a substance,
what do you need to measure?
- The mass
- temperature rise
- the time taken
