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13.1 TEMPERATURE I can… -identify increases/ decreases in temperature as a function of the difference in thermal energy lost or absorbed.

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Presentation on theme: "13.1 TEMPERATURE I can… -identify increases/ decreases in temperature as a function of the difference in thermal energy lost or absorbed."— Presentation transcript:

1 13.1 TEMPERATURE I can… -identify increases/ decreases in temperature as a function of the difference in thermal energy lost or absorbed.

2 THERMAL ENERGY: THE KINETIC ENERGY OF A SUBSTANCE’S ATOMS

3 TEMPERATURE AND ENERGY  Temperature: a measure of how hot (or cold) something is; specifically, a measure of the average kinetic energy of the particles in an object.  Is it possible to find the kinetic energy of every particle in an object and calculate its average?  How is temperature calculation?  Thermometer: uses Mercury or colored alcohol to expand as temperature increases, which allows particles of the liquid to move up the little tube.

4 FAHRENHEIT VS. CELSIUS

5 THE KELVIN SCALE IS BASED ON ABSOLUTE ZERO  Absolute zero: the temperature at which molecular energy is at a minimum (0K on the Kelvin scale or - 273.16 o C  T k = t c +273

6 MATH PRACTICE  The highest atmospheric temperature ever recorded on Earth was 57.8 o C. Express this temperature bath in degrees Fahrenheit and in kelvins.  T f = (1.8 x 57.8) + 32.0=104 + 32= 136 o F  T k =57.8+273=331K

7 QUICK LAB: HOW DO TEMPERATURE AND ENERGY RELATE?  Analysis  Which cup had the higher final temperature?  Both cups had the same starting temperature. Both sets of washers started at 100 o C. Why did one cup reach a higher final temperature?  The cup with 30 washers reaches a higher final temperature because a greater mass (of 30 washers opposed to 10 washers) can transfer more energy.

8 TEMPERATURE CHANGES INDICATE AN ENERGY TRANSFER  Heat: the energy transferred between objects that are at different temperatures  What happens to glass of ice water if you hold it in your hands for a long period of time?  Do M&M candies really melt in your mouth and not your hand?

9 13.2 ENERGY TRANSFER I can… -recognize that conductors have a high rate of energy transfers and insulators have a low rate. -identify the factors that affect rate at which thermal energy is transferred.

10 METHODS OF ENERGY TRANSFER  Thermal conduction: the transfer of energy as heat through a material  Convection: the movement of matter due to differences in density that are caused by temperature variations  Convection current: the vertical movement of air currents due to temperature variations.  Radiation: the energy that is transferred as electromagnetic waves, such as visible light and infrared waves.

11 CONDUCTORS AND INSULATORS  Any material through which energy can be easily transferred as heat is called a conductor.  Examples?  http://examples.yourdictionary.com/examples-of-heat- conduction.html http://examples.yourdictionary.com/examples-of-heat- conduction.html  Insulators prevent energy transfer.  Exampels?  Winter coats, house/attic insulation. particle collision.  ***Remember energy is transferred through particle collision.

12 SPECIFIC HEAT  Specific Heat: the quantity of heat required to raise a unit of mass of homogeneous material 1 K or 1 o C in a specified way given constant pressure and volume.  Energy=(specific heat (c)) x (mass) x (temperature change)  Practice: how much energy must be transferred as heat to the 420 kg of water in the bathtub in order to raise the water’s temperature from 25 o C to 37 o C? Substancec(J/kg x K)Substancec(J/kg x K) Water (liquid4186Copper385 Steam1870Gold129 Ammonia (gas)2060Iron449 Ethanol (liquid)2440Mercury140 Aluminum897Lead129 Carbon (graphite) 709Silver234


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