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    الى طلاب الصف السادس 2011

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    atwa
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    تاريخ التسجيل : 22/04/2009
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    الى طلاب الصف السادس 2011

    مُساهمة من طرف atwa في الثلاثاء أكتوبر 12, 2010 10:17 pm

    Give reasons for unit one
    *-The mass of a pen on the Earth’s surface equals the mass of the same pen on the moon’s surface.
    Because the mass is a fixed value and it doesn’t change by changing the place.

    *- The book has a mass.
    Because it has amount of matter in it.
    *- Jewels are measured by gram, while fruits are measured by kilogram.
    Because gram is suitable for measuring small masses, while kilogram is suitable for measuring large masses.

    -* The mass of two bananas equals the mass of one apple.
    Because the amount of matter in the two bananas equals the amount of matter in one apple.

    -* Object’s falling downward Earth.
    Due to the effect of gravitational forceقوه الجاذبية الأرضية
    *- In the spacecraft, all bodies are in a free fall state.
    Due to the weightlessness.عدم الجاذبية

    *- We can measure the weight of any object by the spring scale.
    Because the extension of its wire equals the weight of the object.



    *- The relation between weight of an object and its mass is a direct relationship.
    Because by increasing the mass of the object, its weight increases. As weight = mass x 10

    *- The weight of any object on the Earth’s surface increases by increasing the object’s mass.
    Because weight is directly proportional to mass, where weight = mass x 10

    *- The weight of a person on the Earth’s surface is larger than that on the moon’s surface.
    Because gravitational force of Earth is greater than moon.

    *- The weight of a bag in a balloon is smaller than that on Earth.
    Because the weight of the bag decreases when the distance between the bag and the center of Earth increases.

    ** Cooking utensils are made of copper, aluminum or stainless steel.
    Because they let heat flow through as they are good conductors of heat.

    **The handles of cooking utensils are made of plastic or wood.
    Because they don’t let heat flow through as they are bad conductors of heat.



    * Air is an insulator, while copper is a heat conductor
    Because air doesn’t let heat flow through, while copper allows heat to flow through.

    * In the insulating glass window, there is a space filled with air between the two glass sheets.
    To prevent the leakage of heat.

    *- Heat is an important form of energy in our daily life.
    Because it is used in Warming the house, Heating water washing clothes. And Cooking.

    *- Heat has countless usages in industry. الحرارة لها استخدامات عديدة فى الصناعة
    Because it is used in making and processing food, glass , paper, textiles

    * If you touch a glass of hot water, you will feel hot.
    Because heat transfers from the high temperature object (hot water) to the lower temperature object (hand).

    *- If you hold a piece of ice, you will feel cold.
    Because heat transfers from your hand (high temperature object) to the piece of ice (lower temperature object).

    *- Copper, iron and aluminum are good conductors of heat.
    Because they allow heat to flow through them.


    * Wood, glass, plastic and paper are bad conductors of heat (insulators).
    Because they do not let heat flow through.
    * Leaving spaces between the railway bars.
    To avoid train accidents where, iron is a good heat conductor that expands and twists by heat.
    * Frying pan is a good conductor of heat.
    Because it allows heat to flow through.

    * Wood is an insulator.
    Because it doesn’t let heat flow through.
    * Copper differs from iron and aluminum in conducting heat.
    Because copper conducts heat faster than aluminum and iron.

    * Kettles are made of aluminum or stainless steel.
    To allow heat to flow through as they are good heat conductors.
    * Aluminum, copper and stainless steel are very important heat conductors.
    Because they are used in making cooking pots (utensils) and kettles that are used in houses and factories.
    * The handles of kettles and cooking pots are made up of wood or plastic.
    Because they are bad conductors of heat (insulators).

    * The handle of iron is made of plastic.
    Because it doesn’t let heat flow through as it is a bad conductor of heat (insulator).
    * We used the heat insulators as wool in making heavy blankets and woolen clothes.
    To keep our bodies warm as they prevent the leakage of heat.

    * Heat insulators are very important in our daily life.
    Because they are used in Making the handles of,Cooking pots utensils Kettles.
    • Iron.). Making the heavy blankets and woolen clothes.

    * We can’t measure the temperature of objects by touching.
    Because the sense of touching helps us to know if the object is hot or cold only, but it cant measure the temperature accurately.
    * Doctors use thermometers in hospitals.
    To measure the body temperature of the patients

    * When you put a straw in a bottle of liquid, the liquid rises in the straw when the bottle is heated.
    Because liquids expand by heating and contract by cooling.

    * There is a constriction above the mercury bulb in the medical thermometer.
    To prevent mercury from going back to the bulb quickly when we read the measurement

    * The medical thermometer must be put in ethyl alcohol before using.
    To sterilize it before using.

    * We must shake the medical thermometer well before using.
    To force the mercury back to the mercury bulb.

    * The thermometer must be kept out the reach of children.
    Because the used liquid in the thermometer (mercury) is toxic.سام
    * The medical thermometer can’t measure the temperature of iced water.
    Because the scale of the medical thermometer ranges from 35 C◦ to 42 C◦ and the temperature of iced water is zero C◦ .

    *- We can’t measure the boiling point of water by using the medical thermometer
    Because the scale of the medical thermometer ranges from 35 C◦ to 42 C◦ and the boiling point of water is 100 C◦

    *- Celsius thermometer can’t be used to measure the human body temperature.
    . Because the Celsius thermometer has no constriction so, it can’t measure the body temperature accurately.
    *-. Mercury is the suitable liquid to be used in making thermometers.
    . Because mercury is:
    a. A liquid metal that can be seen easily through the thermometer glass.
    b. A good conductor of heat.
    C A regular expanding material.
    d. Doesn’t stick to the walls of the capillary tube.

    What happens when unit one :
    * The mass of an object increases.
    Its weight increases.
    * You hang a body in the bottom hook of the spring scale.
    . The object pulls the wire of the spring downwards and the reading of the pointer increases.
    *The mass of the planet where the object exists increases.
    The weight of this object increases.
    *The mass of an object decreases to half.
    The weight of this object decreases to half.
    *The distance between a person in a balloon and the center of Earth increases.
    The weight of the person decreases.

    *You measure the weight of a toy car on the Earth’s surface, then measure its weight on the moon’s surface.
    The weight of the toy car on the Earth’s surface equals 6 times that on the moon’s surface.
    *The gravitational force of a ball increases.
    The weight of this ball increases.


    What happens when unit two :

    * When you touch a hot cup of tea.
    You feel hotness due to the transfer of heat from the hot cup to my hand.


    * When you hold a piece of ice with your hands. .
    You feel coldness due to the transfer of heat from my hands to the piece of ice.
    * When you touch one end of a copper rod, where the other end is exposed to the flame of a candle.
    You feel hotness, because copper is a good conductor of heat.
    * When you touch the end of a glass rod, where the other end is exposed to the flame of a candle.
    You don’t feel hotness, because glass is a bad conductor of heat (insulator).
    * When you pour boiled water in a container that contains ruler and metallic spoon, where each of them has a button.
    The button falls from the metallic spoon faster than that falls from the ruler.
    * When there is no space filled with air between the two glass sheets in the insulating glass window.
    heat will leak .تتسرب
    * When there are no spaces between the railway bars.
    The train accidents may be occur.
    * When you put some cubs of ice in a cooking pan and put the same cubes on a glass sheet. Why?
    The cubes of ice in the cooking pan melts faster than the cubes of ice on the glass sheet, because the cooking pan is a good conductor of heat.
    * When the handles of kettles and cooking utensils are made of stainless steel.
    We can’t hold them with our hands as stainless steel is a good conductor of heat.

    *The medical thermometer is not sterilized before use.
    We may be infected by some diseases.

    * A bottle of colored water is put in a beaker of hot water.
    The colored water rises up in the bottle because liquids expand by heating.

    * A bottle of colored water is put in a beaker of iced water.
    The level of the colored water falls down because liquids contract by cooling.

    * A medical thermometer is put in a boiled water.
    The medical thermometer will be damaged because the boiling point of water is 100 C◦

    * There is no constriction above the mercury bulb in the medical thermometer
    The mercury will return back to the mercury bulb before determining the temperature reading.
    *Water is used instead of mercury in making thermometers.
    The thermometer can’t measure the temperature because water can’t be seen through the thermometer glass tube.
    *We don’t shake the medical thermometer well before use.
    We can’t measure the temperature accurately.
    [b]

      الوقت/التاريخ الآن هو الجمعة أكتوبر 20, 2017 12:25 pm