Thermal energy Flashcards
(33 cards)
What is the SI unit of temperature?
kelvin (K)
What generally happens to solids, liquids, and gases when thermal energy is absorbed?
They expand.
What generally happens to solids, liquids, and gases when thermal energy is given out?
They contract.
What results from thermal expansion?
A change in volume and density of the substance.
What are the three main ways to transfer thermal energy?
- conduction
- convection
- radiation
How does the rate of thermal energy loss or gain by a body through radiation get affected?
- colour and texture of the surface
- surface temperature
What is thermal energy?
The energy possessed by a system due to its temperature.
How is thermal energy transferred between objects?
From a region of higher temperature to a region of lower temperature.
What is the difference between thermal energy and temperature?
Temperature is a measure of the average kinetic energy of particles.
What is the SI unit for thermal energy?
joule (J)
What happens to objects when they are heated?
They generally expand and become less dense.
What happens to objects when they are cooled?
They generally contract and become denser.
Which state of matter expands the least when heated?
Solid
Which state of matter contracts the most when cooled?
Gas
What is a bimetallic strip?
A strip made of two metals that expand at different rates with temperature change.
What is conduction?
The transfer of thermal energy through a medium without physical movement of the medium itself.
Which state of matter conducts heat best?
Solid
Why are metals better conductors of heat than non-metals?
Metals have free electrons that transfer energy quickly.
What is convection?
The transfer of thermal energy due to the movement of the medium arising from density differences.
What is radiation?
The transfer of thermal energy in the form of infrared radiation without the need of a medium.
What factors affect the rate of radiation?
- Nature of the surface (texture and color)
- Surface area
- Surface temperature
True or False: A darker surface absorbs radiation faster than a lighter surface.
True
What unusual behavior does water exhibit when cooled to below 4 °C?
Water expands instead of contracting.
What is the significance of the density of ice compared to water?
Ice has a lower density than water, allowing it to float.
