Physical Properties Of Materials Flashcards
What is compressive strength?
Strength of an object that stops it from being crushed, or changing shape when it is pushed or squeezed
What is tensile strength?
Strength of an object that stops it from breaking when it is pulled apart
What is flexibility?
Ability to bend easily
Give three examples of materials with compressive strength.
Concrete
Rocks
Bricks
Give and example of a material with tensile strength.
Steel
What can flexible materials do?
Bend without breaking
Give an example of a flexible material.
Rubber
Give three examples of when we use flexible materials.
. A rubber garden hose to water the garden
. Car tyres
. Fabrics for clothes
What does melt mean?
When a substance changes from a solid to a liquid
Define melting point.
Temperature at which a substance melts as it changes from a solid to a liquid
What does boil mean?
When a liquid starts to bubble and change into a gas
Define boiling point.
Temperature at which a liquid turns into a gas
What are electrical conductors?
Materials that allow electricity to move through them
What are electrical insulators?
Materials that do not allow electricity to move through them
Define electrical conductivity.
Ability of a material to allow electricity to move through it
At what temperature does ice melt?
Around 0°C
We call this the melting point of ice
At what temperature does water boil?
Around 100°C
We call this the boiling point of water
Notice that we say ‘around’ 0°C or 100°C. This os because conditions are not identical at all times. What can be different? Give an example.
Pressure and impurities, such as chemicals in the water, make a difference to melting and boiling points. For example, water boils at about 96°C in Johannesburg because of the lower air pressure there
Which metal has the highest boiling point?
Tungsten has the highest boiling point (5555°C)
What do we use electrical conductors for?
We use the property of electrical conductivity pf materials like copper and aluminum to make electrical wiring
What do we use electrical insulators for?
Electricity can be very dangerous so we use materials with the electrical insulation property such as rubber and plastic to protect and cover the electrical wires
What is heat conductivity?
Ability of a material to allow heat to flow through it
What is thermal conductivity?
A synonym for heat conductivity
What are thermal insulators?
Materials that prevent heat from flowing through them or that reduce the rate at which heat flows through them
What are variables?
Factors that can change, are observable and measurable
Give an example of how both thermal conductors and thermal insulators can be used in every day life.
If you are cooking in a pot on the stove, the pot is usually made of metal such as copper or aluminum (metal conducts heat), but the handle is usually made of wood ar hard plastic (wood and plastic are thermal insulators)
What happens to the temperature of water once it has reached its boiling point?
It does not continue increasing. It will continue boiling at the same temperature until all of it has evaporated
What other factors are taken into consideration when selecting suitable materials?
Appearance, style, colour, texture and cost. We cannot always combine all the factors that we want so we have to choose which factor is the most important. For example, a metal item might need to be very light and strong. Titanium is perfect for this, but using titanium is extremely expensive, so we use aluminum instead
