Please enable JavaScript.
Coggle requires JavaScript to display documents.
Heat Energy and Temperature - Coggle Diagram
Heat Energy and Temperature
Heat Energy
Form of Energy
Makes things hot
NOT matter
We can feel its effects by sense of touch
Sources of Heat Energy
They produce heat
Main source of heat
Sun
Keeps Earth warm
Other sources of heat
Fossil Fuels
Petroleum
Oil
Coal
Natural Gas
Wood
Sources of light and heat
Sun
Gives
Sunlight
Heat
Fuels
Gives
Light
In the form of fire
Heat
Electrical Appliances
Toaster
Water Heater
Oven
Electric Iron
Rice Cooker
Difference between Heat Energy and Temperature
Heat Energy
Form of Energy
Amount of Heat Energy in An Object
An object containing
A greater amount of heat energy
Hotter
Higher temperature
A lesser amount of heat energy
Colder
Lower temperature
So
2 more items...
Amount of Matter in An Object
Bigger object
Same temperature
More heat energy
Smaller object
Same temperature
Less heat energy
Temperature
Measurement of the degree of hotness/how hot or cold an/in object
Thermometers
Used to measure accurately how hot or cold an object is
Types of thermometers
Laboratory
Used to measure temperature of objects in experiment
Contains a liquid
Mercury
In the glass tube
Alcohol
Measures a longer range of temperatures
10 to 110 degrees celsius
Clinical
Used to measure the temperature of the human body
Measures temperature with
Digitally
Liquid
Measures a shorter range of temperatures
35 to 42 degrees celsius
Units for measuring temperature
Degree Fahrenheit
Degree Celsius
Using thermometers
Reading
Eyes must be at the same level as the liquid in the thermometer
Positioning
Bulb of thermometer must be placed vertically in the liquid
Heat Flow
Heat always flows from
a hotter object (higher temperature)
a colder object (lower temperature)
An object
Can lose heat
Can gain heat
From another object/matter
Through heat flow
Effects of Heat Gain/Loss
Causing change in temperature
Object
Gain heat
Temperature increases
Lose heat
Temperature decreases
Changes in State of Matter due to Heat Gain/Loss
When an object
Gains heat
Loses heat
It can change its state of matter
Changes in State of Matter due to Heat Gain
Solid
Gains heat and melts
Liquid
Gains heat and boils and evaporates
Gas
Changes in State of Matter due to Heat Loss
Gas
Loses heat and condenses
Liquid
Loses heat and freezes
Solid
During the Process of Change of State in Matter
Matter will continue to
Gain heat
Lose heat
But
their temperature will stay the same
Expansion and Contraction of Matter due to Heat Gain/Loss
Heat flow can cause matter to expand or contract.
When matter gains heat
It expands
Mass remains the same
Volume increases
Particles in a substance gain heat and kinetic energy
Motion increases and they push further apart and occupy more space
Density increases
When matter loses heat
It contracts
Volume decreases
Motion decreases
occupy less space
Density increases
Mass remains the same
Uses of Expansion/Contraction of Matter in Daily Life
Opening the lid of a tightly-closed bottle
Running the lid under hot water
lid gains heat from hot water and expands
We can easily open the bottle lid as it is now bigger than the opening of the bottle.
Measuring temperature using a laboratory thermometer
When the thermometer is placed in a hot object
The liquid in thermometer gains heat from the hotter object and expands
The liquid moves up the scale.
When the thermometer is placed in a cold object
The liquid in thermometer loses heat to the colder object and contracts
The liquid moves down the scale.
Problems/Solutions caused by expansion/contraction in matter
Hot water is poured into a glass container
Problem
Glass container gains heat from hot water and expands unevenly, cracking
Solution
Two walls for glass container
Inner wall gains heat and expands first
Glass is a poor conductor of heat and does not conduct heat quickly between both walls
Railway tracks
Problem
If railway tracks are built in a continuous way
They will buckle when they gain heat and expand on hot days
Solution
There are small gaps along the tracks
The tracks will now not buckle when they gain heat expand on hot days
Overhead electricity cables
Problem
If overhead electricity cables are hung tightly between poles
They will lose heat and contract and snap on cold days
Solution
Overhead electricity cables are then hung loosely between poles
They will not snap when they lose heat and contract on cold days
Concrete Roads/Surfaces
Problem
If concrete roads are built in a continuous way
cracks will occur
The road keeps changing in size
Solution
Gaps are left in the roads
there is space for expansion
Pipes
Problem
Expansion
The pipe will expand and burst.
Contraction
The pipe will contract and break apart
Solution
Pipes are coiled
Space to expand
Rate of Expansion/Contraction
Gases
Liquids
Solids
Fast
Slow
Riveting
Holding 2 metal plates firmly together
Rivets
bolts made of steel
a hot rivet is placed into the holes of the metal plates
the other end is hammered until secured
when the rivet cools
it contracts and decreases in size
Placing a wheel in a metal tyre
a wheel is placed inside
a hot and expanded metal tyre
when the metal tyre cools
contracts
wheel is fitted well into tyre
Bimetallic Strip as A Thermostat
device used to regulate temperatures automatically
made of
Brass
Expands
Contracts
Faster
Causing the strip to bend in both directions
Iron
Used in
Electric Irons
Electric Ovens
Fire Alarms
Conductors of Heat Energy
Good Conductor of Heat
Allow heat to flow through them easily
Examples
Metals
Silver
Zinc
Copper
Aluminium
Iron
Steel
Gold
Poor Conductor of Heat
Do not allow heat to flow through them easily
Examples
Glass
Air
Rubber
Fabrics
Plastic
Wood
Thickness of A Material
Can affect the rate of heat flow through a material
When the thickness of a material increases
The rate of heat flow decreases
More time is taken for
Heat Loss
Heat Transfer
Heat Gain
Heat Flow
Uses in Daily Life
Metals
Used to make
Cooking utensils
Heating Elements
In electrical appliances
Toasters
Ovens
Because
They allow heat to flow through them quickly
To cook
1 more item...
To heat up
1 more item...
Wool
Fur
Used to make
Shoes
Winter clothing
Because
They are poor conductors of heat
People can keep their bodies warm in a cold environment
Feathers
Plastic
Used to make
Handle of a cooking pan
Because
They do not allow heat to flow through them easily
We can hold the handle of the cooking pan safely
General Situations
A metal spoon feels colder than a plastic spoon at the same temperature
Metals are better conductors of heat than plastic
When we touch the metal spoon and the plastic spoon
Metal conducts heat away from our hand faster than plastic does
Our hand loses heat faster when we touch the metal spoon
Our feet feel colder when we walk on a marble floor than a wooden floor at the same temperature
Marble conducts heat away from our feet faster than wood does
Convection in Liquid and Gas
Liquid
Experiment
A beaker with blue crystals at the bottom is heated.
The circulation of the blue stream of water moving up and down is called the convection current.
Explanation
As water is heated up
it expands and its density decreases
it rises up
the cooler part of the water which is denser sinks to replace the heated water
cycle is repeated to form the convection current
Gas
Experiment
A box with 2 chimneys
Chimney 1
Candle below
Chimney 2
Smouldering paper on top
Smoke from smouldering paper flows down into the chimney and moves towards the lit candle and goes up through the other chimney
Explanation
Air above the lit candle is heated and expands and rises out through the chimney
The cooler surrounding air is denser at the other chimney
So it sinks through the chimney to replace the hot air
Use in our daily life
Electric Kettle
When electricity is turned on, the heating element which is placed at the bottom of the kettle heats up the water at the bottom
Hot water rises and cold water sinks
Thus a convection current is set up in the kettle water in the kettle is heated up more uniformly and effectively
Hot water system
Water is heated up in the boiler which is installed at the lower part of a hot water system
hot water rises to the upper part of a storage tank
cold water in the water supply tank sinks into the boiler to replace the hot water
Cold air from the air conditioner sinks into the room
Hot air rises and it is cooled by the air conditioner and then sinks down
The cycle is repeated to set up convection currents in the room
Convection in Natural Phenomena
Sea Breeze
During the day, the land is heated up faster than the sea
thus the air above the land is warmer than above the sea
so it rises up the cooler and denser air from the sea flows in to replace the rising hot air
Land Breeze
During the night the land loses heat much faster than the sea
The air above the sea is warmer than above the land. It rises up and the cooler and denser air from the land flows towards the sea to replace the rising hot air.
Radiation
Black
Dull
Surfaces
Best absorbers and emitters of radiant heat
They are the poor reflectors of heat
Rough
White
Surfaces
Poor absorbers and emitters of heat
Good reflectors of heat
Shiny
Smooth
Hot water containers
The hot water containers have a shiny appearance to reduce heat loss by radiation from inside the containers to the surroundings. In this way, water can stay warmer for a longer period of time.
White clothes
White color is a poor absorber of heat. When a person walks under the hot sun, he will not feel overheated if he puts on white clothes
Refrigerator
The cooling coils of a refrigerator are painted black to ensure that heat is lost quickly as black color can radiate heat faster to the surroundings
Vacuum Flask
Stopper
Prevents the set-up from convection current
Convection
Trapped Air
Good insulator of heat
Conduction
Vacuum
No particles
Conduction
Convection
Silvery Glass Walls
reflects heat back into liquid
radiation