Temperature, Heat, and Thermal Energy

1. Temperature, Heat, and Thermal Energy

2. What is Temperature? Particles of matter are in constant motion. This motion relates directly to the state of matter of the object (solids, liquids, or gases). Temperature affects how fast these particles move. The higher the temperature, the faster the particles move. Moving particles possess kinetic energy. Temperature is defined as the average kinetic energy of the particles of an object.

3. Energy of different objects may fall into two main categories: Kinetic Energy and Potential Energy GET SOME FAST POINTS!! Write the Definitions for Potential and Kinetic Energy In Your Own Words! 20 SECONDS – GO!!!

4. CHECK YOUR ANSWERS!!! Kinetic Energyis the energy of a moving object! • Potential Energyis stored energy. • Energy in our bodies or in a battery is called chemical potential energy • and… • Energy due to the position of an • object above the surface of the earth is gravitational potential energy.

5. Thermal Energy and Temperature: Thermal Energy is the sum total of all of the energy of the particles of an object. Thermal energy and temperature are related, though DIFFERENT. Temperature is the average kinetic energy of the particles of an object. Thermal energy is the total amount of energy of the particles of an object. ?? A bathtub full of water at 100F has more thermal energy than a thimble of water at 100F. WHY????

6. Thermal Energy and Temperature: More water at the same temperature = more thermal energy!! Less water at same temperature = less thermal energy

7. 80ºC 80ºC 400mL A B 200mL Thermal Energy • Which beaker of water has more thermal energy?

8. 80ºC 80ºC 400 mL A B 200 mL Thermal Energy - Answer • Which beaker of water has more thermal energy? • B because it has more MASS!!!

9. Let’s Sum Up Temperature and Thermal Energy! • Temperature is a measure of the average heat, or thermal energy, of the particles in a substance. Because it is an average measurement, it does not depend on the number of particles in an object. It only depends on the amount of movement of those particles. • Thermal Energy is the amount of movement the particles have. Increasing the amount of movement of the particles can increase the amount of heat it has; therefore it will increase its temperature!!

10. Then, what is HEAT? Heat is really the amount of thermal energy being passed from one object to another. Heat travels in a specific direction—ALWAYS from the warmer object to the cooler object. So, if heat is the amount of thermal energy, then the amount of heat an object has tells me how much kinetic energy the object has. Ice = cold temp and very little movement, so very little heat/kinetic energy/thermal energy of its particles!!! Fire = high temp and a lot of movement, so high heat/kinetic/thermal energy!!!

11. 80ºC 10ºC A B Heat Transfer • Why does A feel hot and B feel cold?

12. 80ºC 10ºC A B Heat Transfer Answer • Why does A feel hot and B feel cold? • Heat flows from A to your hand = hot. • Heat flows from your hand to B = cold.

13. When we take a temperature we are seeing how much heat has been transferred in to an object. Based on the amount of heat, the particles will move a lot or a little. Movement can keep the temperature constant or increase/decrease it. Therefore, temperature is directly related to heat and heat is the amount of thermal energy passed to an object!!! So…

14. Temperatures You Need to Know: It is important to know the freezing and boiling points of water. Absolute zero refers to the temperature at which all movement of particles in an object would stop!

15. Time for Kids to Think Answer the following: • What happens to the atoms or particles as temperature increases? Decreases? • Think of water: at low temperatures, water freezes and becomes a solid, as temperatures increase the ice melts to become a liquid. As temperatures rise even more, the water evaporates to become a gas… Do the particles move faster in a solid, liquid or gas? Why do you think this? Explain your answers in writing!

16. Answers! Click following Link to see movement of particles at different temperatures: http://www.colorado.edu/physics/2000/bec/temperature.html In cold objects, the molecules move slowly and in a hot object the molecules move faster! Particles/atoms/molecules move fastest in a gas!

17. How is Thermal Energy Transferred? 3 MUST KNOWS!!!!! Conduction – throughdirect contact! Convection – through a gas or liquid , moves in currents! Radiation – electromagnetic waves through empty space, no medium required!

18. Transfer of Thermal Energy: Conduction

19. Transfer of Thermal Energy: Convection

20. Thermometers: Bulb thermometers rely on the simple principle that a liquid changes its volume relative to its temperature. Liquids take up less space when they are cold and more space when they are warm. (This same principle works for gases too, and is the basis for how a hot air balloon works).

21. Thermometers: All bulb thermometers use a fairly large bulb and a narrow tube to accentuate the change in volume. So as heat is transferred, the movement—or thermal energy—of the particles that make up the liquid in the bulb increases, and it can only move up! As amount of heat decreases, the movement of particles decreases, so liquid moves back down!

22. INTERESTING INFO!! • Do not take temperatures directly after drinking hot or cold liquids or immediately after working out!!! • DO YOU KNOW WHY????

23. Heat TransferSummed UP! • Heat: • Thermal energy that flows from a warmer material to a cooler material and, • Like work, heat… • is a transfer of energy! • can be measured in Joules (J).

24. A Review of Temperature, Heat, and ThermalEnergy Plus, A Little More Information!

25. Heat Transfer • Heat is always transferred from hot to cold. • Insulators slow the transfer of heat/energy. • Conductors (like metals) allow the transfer of heat. • Heat is transferred by conduction, convection, and radiation.

26. Conduction • Heat is transferred due to objects touching each other or through collisions. • Occurs best through solids • Heat continues to be transferred until both objects reach the same temperature, called athermal equilibrium.

27. Convection • Transfer of heat through a liquid or gas, through moving currents (called convection currents). • The cause of wind and weather

28. Radiation • Transfer of heat through electromagnetic radiation waves, like from the sun, a fire, or a light bulb. • Transferred in all directions • No contact required! • Dark or dull objects absorb more than light or shiny objects do.

29. A Little History: Temperature and Atoms • In 1827, the biologist Robert Brown noticed that if you looked at pollen grains in water through a microscope, the pollen jiggles about. He called this jiggling 'Brownian motion', but Brown couldn't work out what was causing it. • Einstein, who was 26 years old at the time, published 3 papers in 1905 explaining Brown’s discovery.

30. Just What Did Einstein Discover? • Einstein assumed that substances existed as atoms that moved about randomly. • Reason: a pollen particle in water, moves randomly because it is being hit by moving water molecules randomly from all different directions!

31. See an example of Brownian motion • Click on link below to see how Brownian motion of gas molecules can make a larger dust particle move around randomly. • Click here.

32. Temperature Related to Reactions: • Heat provides the energy for Brownian motion. The more heat, the more molecules move. • When molecules move, they have a better chance to collide with other molecules which leads to Chemical Reactions!

33. Warm-blooded, cold-blooded, and human body systems related to temperature

34. What does it mean to be warm-blooded? • Warm-blooded creatures, such as mammals and birds, try to keep the inside of their bodies at a constant temperature. • They do this by generating their own heat when they are in a cooler environment and by cooling themselves when they are in a hotter environment. • To generate heat, warm-blooded animals convert the food that they eat into energy. • They have to eat a lot of food, compared with cold-blooded animals, to maintain a constant body temperature. • Only a small amount of the food that a warm-blooded animal eats is converted into body mass. The rest is used to fuel a constant body temperature. Thermal imaging of boy Thermal imaging of birds

35. Adjusting Chemical Reactions That Generate Body Heat • Chemical reactions can generate energy, some of which is “lost” as heat (Click here to learn more.) • The source of heat energy is food. • Therefore, warm-blooded animals tend to have more difficulty dealing with scarcity of food.

36. How Warm-Blooded Animals Regulate Body Temperature: • Shivering begins when the nervous system senses the body’s internal temperature dropping. The contracting of muscles leads to shivering, which, in turn, raises body temperature. • When the nervous system senses an increase in body temperature, it creates responses that will help lower it (a dog panting or a human sweating).

37. Thermoregulation/Negative Feedback Mechanisms: • Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. This process is one aspect of homeostasis: a dynamic state of stability between an animal's internal environment and its external environment. This is a form of Negative Feedback.

38. What is Negative Feedback? • Functions such as blood pressure, respiration, and blood glucose levels—as well as body temperature—are all regulated through negative feedback. • The body's homeostasis is maintained by negative feedback mechanisms, sometimes called negative feedback loops. • In negative feedback, any change or deviation from the normal range of function is opposed, or resisted. The goal of negative feedback is to bring the function of the organ or system back to within the normal range.

39. What is a Fever? • A fever is characterized by an elevation in body temperature, usually by about 1-2oC. • The body notices an invading organism. The body’s goal is to remove the invader so it “re-sets” its “thermostat”. This can happen after getting a vaccination as well. • Common symptoms of having a fever are a cold sensation, shivering, and an increase in heart rate.

40. Why Do We Get Fevers? • Infectious diseases (such as influenza and the common cold) are the most common reason for fevers. • Disease-causing microorganisms have a more difficult time living in higher temperatures. • Also, white blood cells (which kill microorganisms) tend to operate more effectively when a fever exists. • So, the body raises its internal temperature to make an unfriendly environment for the invader and to assist the activity of the white blood cells!! • Once the invader is no longer an issue, the body will resume normal temperature function yet again.

41. Advantages Since mammals and birds can maintain a constant internal body temperature, they can actively live just about anywhere! As a result of being more susceptible to infection, they are inclined to have a better immunity to diseases. Disadvantages Given that the majority of energy used is in generating heat, warm-blooded animals must consume large amounts of food. Also, because of their high body temperatures, it is easier for parasites, viruses, and bacteria to infect warm-blooded animals. Warm Blooded Review:

42. Cold-blooded Animals Cold-blooded creatures take on the temperature of their surroundings. They are hot when their environment is hot and cold when their environment is cold. In hot environments, cold-blooded animals can have blood that is much warmer than warm-blooded animals. Cold-blooded animals are much more active in warm environments and are very sluggish in cold environments. This is because their muscle activity depends on chemical reactions which run quickly when it is hot and slowly when it is cold. A cold-blooded animal can convert much more of its food into body mass compared with a warm-blooded animal.