Physics Yr 8 Flashcards
Diffusion means
Gasses or liquids mix without anything moving them because the particles are moving around all the time.
Brownian motion means
Tiny speaks of dust in air or water can be seen jiggling around as they hit by the moving air or water particles
What do solids do
They keep their shape and volume but they cannot flow and are difficult to compress
What do liquids do
They keep their volume but not there shape and they can flow/they take the shape of there container and are difficult to compress.
What happens to the energy when a substance cools down?
The energy is transferred away - decreases
Expansion joints in bridges are built in because?
The material contracts in the cold and expands in the heat. In heat the materials would crush together and break.
How does a thermometer work?
The liquid -alcohol, expands in heat and rises up the tube.
Particle theory
STATE>FORCES>SPACING>MOVEMENT
Solid>strong>close>vibration in fixed position.
Liquid >fairly strong>close>move around with the liquid.
Gas>weak>far apart>move about fast in all directions.
Calculating density
Density =mass divided volume
What happens to water when it boils
The mass stays the same and the volume and density decreases
Density
A quantity that cannot be measured directly it has to be calculated using measurements of mass and volume
Volume
An object changes without its mass changing (usually because it has been heated or cooled) its density will change.
What is sublimation
Some material including ice can change directly from a solid to a gas
Chemical changes
Changes such as combustion and neutralisation because the atoms with in substances become come bind in different ways to form new substances
Physical changes
Chemicals in the substances do not change
