Opening Assignment 1. What page does Chapter 14 Sec 1 start? 2. What are the first 2 key concepts? 3. Preview the pages what do you think you are going to learn about. 4. Page 474 – what are the three common temperature scales?
Thermal Energy Temperature and Heat
Temperature If the weatherperson tells you its going to be 20 degrees out, what are you going to wear? Do you need a coat when you go outside? Or only shorts and a T shirt? What you decide depends on what 20 degrees means.
What is Temperature? It is a measure of the average kinetic energy of the particles in a substance.
What happens when the temperature of an object is increased?
What happens when things get hot? Their molecules move faster -- they have more kinetic energy. Most substances EXPAND when they get hot!
Expansion Joints in bridges
Eureka – expansion and contraction Episode 21
What happens when things get cold? Their molecules slow down. Most substances contract….(get smaller)
Example Why does water appear on the side of a cold glass of ice water in the summer?
Water is one of the few substances that expands when it gets cold.
Potholes - They happen because water change state!
How do you measure temperature?
Eureka Episode 20 Measuring Temperature
Measuring Temperature 1. When you measure the temperature of something, what are you really measuring? 2. Anders Celsius came up with the Celsius scale to measure temperature or degree of hotness… How did he do this?
Anders Celsius
How do thermometers work? Thermometers consist of a liquid – alcohol or mercury – sealed in a glass tube. Heat is added Particles in the liquid start to move faster and spread out Liquid in the Thermometer rises
Temperature scales Three common scales of temperature Fahrenheit scale Celsius Kelvin
Know these important temperatures! Freezing/melting point of water is 32 degrees F or 0 degrees C. Boiling point of water - 212 degrees F or 100 degrees C. Body temperature - 98.6 degrees F or 37 degrees C The temperature at ABSOLUTE ZERO It is a theoretical point at which all molecules and atoms stop moving……
Absolute Zero Dream Achieved
Mr… Edmonds – Are heat and temperature the same thing?
Thermal Energy and Heat Are they the same thing?????
Thermal energy- What is it? Thermal energy is total kinetic energy of the particles in an object. Atoms and molecules are always in constant motion! Think of it as the internal energy of all the particles in an object. It tells you how fast the particles in a substance are moving!
Thermal Energy Temperature Depends on The number of particles in an object Temperature
How is temperature related to Thermal Energy For the same size cups Temperature goes up thermal energy increases Temp. goes down thermal energy decreases Kinetic energy
How is thermal energy related to number of particles? Different size cups Same temperature the cup with more particles has more thermal energy Kinetic energy
Eureka Episode 21 Temperature vs. Heat QUANTITY of HOTNESS = Thermal energy
1. Which should you use to increase the temperature of the bath water, the bucket or the cup? ________. Why? 2. The bucket has more thermal energy than the cup. Explain why.
Heat always flows from warmer to cooler objects. Cup gets cooler while hand gets warmer Heat - What is it? The flow of thermal energy from one object to another. Heat always flows from warmer to cooler objects. Ice gets warmer while hand gets cooler
How is heat transferred for each of these objects?
Graph the temp over time
How is heat transferred for each cup?
Summing up what I have learned ________ _______ is the total energy of all the particles in an object. ______________ is a measure of the average kinetic energy of the particles. The transfer of thermal energy (from warmer to cooler) is called _________.
Radiation, Conduction and Convection Heat transfer Radiation, Conduction and Convection
Specific Heat
Land heats up and cools down faster than water 6. Specific Heat a. Some things heat up or cool down faster than others. Land heats up and cools down faster than water
b. Specific heat is the amount of heat required to raise the temperature of 1 kg of a material by one degree (C or K). 1) C water = 4184 J / kg C 2) C sand = 664 J / kg C This is why land heats up quickly during the day and cools quickly at night and why water takes longer.
Why does water have such a high specific heat? water metal Water molecules form strong bonds with each other; therefore it takes more heat energy to break them. Metals have weak bonds and do not need as much energy to break them.
How to calculate changes in thermal energy Q = m x T x Cp Q = change in thermal energy m = mass of substance T = change in temperature (Tf – Ti) Cp = specific heat of substance
First, mass and temperature of water are measured c. A calorimeter is used to help measure the specific heat of a substance. First, mass and temperature of water are measured Knowing its Q value, its mass, and its T, its Cp can be calculated Then heated sample is put inside and heat flows into water This gives the heat lost by the substance T is measured for water to help get its heat gain