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TOPIC: Heat AIM: What is heat & how is it measured?

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Presentation on theme: "TOPIC: Heat AIM: What is heat & how is it measured?"— Presentation transcript:

1 TOPIC: Heat AIM: What is heat & how is it measured?

2 What you will learn: 1.Define temp. 2.Explain how thermal energy and temp are related. 3.Calculate the change in thermal energy of an object due to temp change.

3 Why is it important: Cars, buses, trucks and airplanes could not operate without thermal energy. Review vocab: Kinetic energy: energy an object has due to motion What is kinetic energy?

4 New Vocab Kinetic theory Kelvin Temp Thermal energy Heat Specific heat

5 Kinetic Theory of Matter Matter is made of molecules that are always in motion which collide & transfer their Kinetic Energy

6 Molecules are always moving which produces heat The more heat that is contained the faster the molecules move

7 What are molecules?

8 Molecules Tiny particles that make up matter

9 Example: 1 molecule of water = H 2 O 5 molecules of water

10 Molecules moving (have KE)

11 What is heat? Energy caused by internal motion of molecules Energy moves from warm  cooler region

12 Temperature Measure of how hot or cold something is Measure of average KE of molecules

13 If heat is added to an object the molecules move ________, which _________ the Kinetic Energy, which causes the temperature to _________. faster increase increases

14 Low temp = slower moving High temp = fast moving

15 The average kinetic energy of the particles in the soup is greater than the average kinetic energy of the particles in the ice cream.

16 70°F The pail of water has fewer molecules in it than the ocean does. Even though they may be the same temperature, the pail of water has less heat than the ocean.

17 Thermometer For measuring temperature Tube filled with a fluid such as mercury

18 Heated  molecules move faster and far apart  Mercury expands & rises up tube

19 Cooled  molecules slow & move closer together  Mercury contracts and drops

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21 Heated Liquid level rises Cooled Liquid level drops

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23 Fahrenheit Scale Non-metric temp scale °F°F

24 Water freezes = 32°F Water boils = 212°F Human body temp = 98.6°F

25 Celsius Scale Metric scale °C°C

26 Water freezes = 0°C Water boils = 100°C Human body temp = 37°C

27 Kelvin scale Metric scale Units = Kelvins (K)

28 Absolute Zero = 0K (coldest temp = when molecules stop moving)

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31 Conversions °C  K Celsius + 273K

32 K  °C Kelvin - 273

33 Example: 56°C = ? K 56 + 273 = 329K

34 Example 400K  ? °C 400 – 273 = 127 °C

35 Changing Temp Increasing  heat ADDED Decreasing  heat being REMOVED

36 How is heat measured? CALORIES unit of heat 1 calorie = 4.184 J Amount of heat needed to raise the temp of 1g of water 1°C

37 1000 calories (1 kilocalorie) = 1 food Calorie

38 Your body uses the calories in food for heat and energy. Some foods contain more calories than others, and therefore provide your body with a concentration of energy. Foods that are high in calories contain large amounts of chemical energy, often more than your body can properly break down and use. What's left over is often stored as fat. That's why people on diets avoid foods that are high in calories.

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40 TOPIC: Heat AIM: What is thermal expansion?

41 Thermal Expansion Expansion (increase in size) of a substance caused by heat Temp increases  molecules move faster & farther apart

42 Examples: 1. The rising of mercury/ alcohol in a thermometer

43 2. Hot air balloons rise because heated air expands

44 When both ball and ring are at room temperature, the ball fits through the ring. When the ball is heated, it no longer fits due to thermal expansion.

45 Spaces between the joints allow the metals in the bridge to expand.

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47 Summary: Recap lesson Read article on thermometer and absolute zero Paraphrase partners?

48 http://www.brainpop.com/science/energy/h eat/zoom.wemlhttp://www.brainpop.com/science/energy/h eat/zoom.weml


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