What are three ways heat can be transferred from one place to another?
Conduction, Convention, Radiation
What is Conduction
Conduction is the transfer of heat energy without the physical movement of the medium
What is convection
Convection is the transfer of heat energy from one place to another by the physical movement of a medium.
What is radiation?
Radiation is the transfer of energy from a hotter body to a cooler body without the need for a medium.
Define Diffusion
Diffusion is a net movement of particles from a region of higher concentration to a region of lower concentration
Define Temperature
Temperature is the measure of how hot an object is
What is the SI Unit of temperature?
Kelvin
Why do the railway tracks have gaps in between?
To provide space for expansion
What is the process called when the size of an object increases?
Expansion
What is the process when the size of an object decreases
Contraction
- When does expansion occur?
- When does contraction occur?
- When the object gains heat
- When the object loses heat in the surrounding temperature
When an object expands, the density of the object decreases.
True or False?
True
When an object contracts, the density of the object remains the same.
True or False
False
When solids expand, why can’t we tell whether the solid really expanded or not?
The expansion in solids is very small. It is not noticeable. This is because the particles in solid cannot move around but only vibrate at fixed positions.
What happens when there is an increase in volume?
The density of the liquid decreases during heating
How is the expansion in liquid faster
This is because the particles in liquids are able to move about while the particles in solids vibrate in a fixed position
Which matter has a better conductor of heat?
Solids. They are generally good conductors of heat compared to liquids and gas
Explain why the ice cubes do not melt immediately even when the water around the surface is boiling.
Water is not a good conductor of heat. It cannot conduct heat very well from the surface to melt the ice cubes at the bottom
A tiled floor feels colder than a wooden floor normally. Explain why it is so.
Tiles are better conductors of heat than wood, so heat is conducted away from our feet faster when our feet touch the tiles.
Why cant convection take place in solids
Because the particles in solids are not able to move about
How does convection in liquid work?
When a part of liquid is heated, the density decreases because the heated liquid expands. Therefore, the hot liquid rises up.
How does convection in a gas work
When a part of gas is heated, it expands and becomes less dense. Therefore, the hot gas rises up. The cooler part of the gas, which has a density higher than the heated gas, sinks down.
In radiation, what does a substance do in the absorber.
Any substance that takes in heat in the form of radiation
During Expansion and contraction, which one remains the same?
- Volume
- Mass
- Density
Mass
