Unite 2:Heat energy

Unite 2:Heat energy

Lesson one: heat conduction


*the temperature of the most important forms of energy used in our daily lives, where we use in homes for heating and cooking and improves water and other
In the field of industry it may use countless industries such as paper, glass, food and other

Heat: is a form of energy that travels from the upper body in the heat to the body at least in the temperature

Temperature:
Is an indicator of how hot or cold objects

Activity1 detection of good conductors of heat and poor conductors of heat:

tools: Glass dish, metal spoon, plastic ruler, Wooden pencil, molten wax, hot water, 3 buttons
steps:
1 -fix a ruler and a pencil and a spoon base of the dish using clay.
2 - paste a button on each of the ruler and pen and a spoon using molten wax.
3 - Pour hot water into the dish so as not to fill the edge
obs: We note that the button on the spoon fell in the dish first

conc: the spoon conduct temperatures better than wood and plastic
so that different materials differ in the conduction of heat.










Activity2 the differences in conductivity of materials to heat

Tools: Flame, a water cup, 4sticks of different materials ((Wood - aluminum - Plastic - Steel))
steps:
1 - we get the four sticks of the substances listed and they are equal in length.
2 - put the cup with the inside of water on the flames, and heat the water and then put the four sticks inside.
3 - Hold the aluminum stick. Do you feel the heat? ........ Yes, of course
4 - Repeat the previous step with the rest of the sticks.
obs: we feel heat When we hold aluminum and iron, we do not feel the heat in the stick of wood and plastic
Conc:
Aluminum iron good conductors of heat and wood, plastic, poor conductors of heat
Materials differ in heat conduction into two types








1 - Materials good conductors of heat:
They are the materials that allow the passage or heat flow through different metals such as copper, iron and aluminum
2 - Materials bad conductors of heat:
They are the materials that do not allow the passage or heat flow through such as wood, plastic, glass and paper

Note:
A person who live in the cold country benefits from the rule that the air is poor connectivity
G.R: In the manufacture of glass windows, left a space between two sheets of glass
Which leads to keep the air inside the house warm and non-diversion of outside


Activity 3: different degree of connectivity to the metal temperature:
tools: two metallic stands, three sticks, metal equal in thickness and length of iron, aluminum, copper, paraffin wax, Pins Office, Flame, stopwatch.
steps:
1 - fix with paraffin wax put little points of molten wax on each stick of the three sticks.
2 - Install a pin on the molten wax before it frozen on each stick
3 - Place the sticks of the three carriers metals.
4 - Put the end of the sticks free of paraffin wax on the flame
5 start calculates the time required to hit the pins on the sticks for each stick and then record in a table
obs:
that the pin on the stick of copper fell first and then the aluminum and iron.
conc:
Metals vary in the degree of heat delivered to where we find that copper faster in the heat conduction of aluminum and iron







Life applications
G.R: Technicians leave spaces between railways so
Does not lead to extended by the summer curving (curvature), leading to an accident

Uses of conductors and insulators:
1 - using good conductors of heat, such as copper and aluminum in the manufacture of pots, spoons and kettles and boilers of factories and power stations. (G.R)
2 - using materials of poor conductors of heat such as wood and plastic in the manufacture of the handles. (G.R)
3 - used heavy woolen clothes in the winter because it is heat-insulated (G.R)





Exercises :
Q 1: Tick (√) or sign (×): -
1 - All metals poor conductors of heat ( )
2 - handles of cooking pots made of copper ( )
3 - in the cold regions Aluminum used in heat insulation ( )
4 – good conductors allow the passage of heat through ( )
5 - Iron faster thermally conductive than copper ( )

Question 2: Type the scientific term:
1 - materials allow the passage of heat through ()
2 - materials that do not allow the passage of heat through ()
3 - an indicator of how hot or cold objects ()

Q 3: Compare the conductive material and insulation material by definition, uses and examples

Q 4: Complete the following statements:
1 - heat is a form of........... Transmitted from the body.................. To the body .............
2 - and use special tools to measure temperature called....................... .
3 - used ................ In the cooking utensil industry, while it uses ................... In the industry handles
4 - when holding a cup of hot tea, the temperature travel from ........... To ....... ... .
5 - used ............. In the winter for heating because it ......................

Q 5: Rate the following materials to conductive materials and insulating materials:
Copper - Iron - Plastic - Wood - Aluminum - Nickel - Glass - Paper - Chalk














Measuring temperature lesson two:

Thermometers
Is a way to measure temperature.

The idea of work: change the size of the liquid by increasing the temperature
the expansion of liquids by heat and shrink in cold.

Kinds of thermometers:

Celsius thermometer
Is composed of a thick glass inside it capillary tube ends with mercury reservoir clinical thermometer
Is composed of a thick glass inside it capillary tube with constriction ends with mercury reservoir

Its graduation stars from 00c and ends with 1000c or 2000c Its graduation stars from 350c and ends with 420c
Used to measure the temperature of liquids Used to measure the temperature of the human
There is no constriction between the reservoir and capillary tube Constriction is made to be able to see the doctor of body temperature after being driven out of the patient




G.R: why we use mercury in thermometers.
1- it is a silver liquid can be easily seen from the glass
2- it is a good conductor of heat
3- it expand by heat with
4-Mercury does not stick to the wall of tube
5 - Mercury is liquid between -39 ° and 357 ° C and this gives a wide range of measuring temperature

Notes:
1 - the temperature of the natural human is 37 degrees Celsius
2 - Do not press on your teeth not to break the thermometer and mercury enters the mouth, leading to poisoning
3 - When you measure the temperature of liquids to be put in the thermometer vertically and have a look to the graduation vertically to the thermometer.
4 - There is some modern digital thermometers to show the temperature in the form of figures such as used to measure the temperature of children


Exercises:

Q 1: Complete the following: -
1 - the idea of working thermometers ....................... Heat and ....................... Cold
2 - There are two types of thermometers thermometer ................... And ............................ .
3 - uses a thermometer ................ In measuring the temperature of the liquids
4 – begin graduation in the medical thermometer ............ and ends with ..............
5 - Mercury is liquid between temperature ................. and ...................

Q 2: Tick (√) or sign (×): -
1 - You can use the hand to know the temperature ()
2 - thermometer centigrade scale starts from zero to 1000or2000
3 - Mercury good conductors of heat ()
4 - Celsius thermometer used to measure the temperature of the human ()
5 - When measuring the temperature of liquids placed the thermometer horizontally into the liquid ()

Q 3: Compare each of:
Thermometer medical Celsius thermometer

Q 4: give reasons:
1 - thermometer has the constriction
2 - does not use a medical thermometer to measure the boiling point of water?
3 - You should shake the thermometer well before the medical use?
4 - You should not rely on the sense of touch when estimating the temperature?