Today’s special Welcome back! New seating chart! Exam results Presentation feedback Late work policy Attendance policy for this class Vocab 16 Thermal E & heat-hw check Video-Einstein’s Big Idea-take notes

Today’s special Vocab 16 Thermal E & heat-hw check Video-Einstein’s Big Idea-take notes Paper due next class Worktime

Today’s special Turn in paper on front desk Notes 16.1 HW I due next time

Late work 1. Do your work on time to enhance your learning and to contribute to the academic environment of the class 2. If you fail to do #1 you can turn in your work late if you attend a full session of homework club -Full credit potential if you attend the next hw club -70% potential if you attend within 1 week -30% potential if you attend within 2 weeks -10% max if turned in by the retest date for that unit MSG turns into 0 at that point

Formal academic environment  Treating pupils with care, fairness and consistency; boosting student-teacher acceptance of diversity; and reducing the emphasis on student competition represent successful methods. It is also important to promote student decision-making, individual and civic responsibility and commitment to the larger school community in order to improve school climate.

Work and Heat In what direction does heat flow spontaneously? Heat is the transfer of thermal energy from one object to another because of a temperature difference. Heat flows spontaneously from hot objects to cold objects.

Temperature What is the temperature of an object related to? Temperature is related to the average kinetic energy of the particles in an object due to their random motions through space.

Temperature Temperature is a measure of how hot or cold an object is compared to a reference point. On the Celsius scale, the reference points are the freezing and boiling points of water. On the Kelvin scale, absolute zero is defined as a temperature of 0 kelvins.

Thermal Energy What two variables is thermal energy related to? Thermal energy is the total potential and kinetic energy of all the particles in an object. Thermal energy depends on the mass, temperature, and phase (solid, liquid, or gas) of an object.

Thermal Energy Thermal energy depends on mass and temperature. The tea is at a higher temperature than the lemonade. The lemonade has more thermal energy because it has many more particles.

Thermal Contraction and Expansion What causes thermal expansion? Thermal expansion is an increase in the volume of a material due to a temperature increase. Thermal expansion occurs when particles of matter move farther apart as temperature increases.

Specific Heat How is a change in temperature related to specific heat? Specific heat is the amount of heat needed to raise the temperature of one gram of a material by one degree Celsius. The lower a material’s specific heat, the more its temperature rises when a given amount of energy is absorbed by a given mass.

Specific Heat

Specific Heat In this formula, heat (Q) is in joules, mass (m) is in grams, specific heat (c) is in J/g•°C, and the temperature change (Δt) is in degrees Celsius.

Specific Heat Calculating Specific Heat An iron skillet has a mass of 500.0 grams. The specific heat of iron is 0.449 J/g•°C. How much heat must be absorbed to raise the skillet’s temperature by 95.0°C?

Specific Heat Read and Understand What information are you given?

Specific Heat Read and Understand What information are you given?

Specific Heat Plan and Solve What unknown are you trying to calculate? What formula contains the given quantities and the unknown?

Specific Heat Plan and Solve What unknown are you trying to calculate? What formula contains the given quantities and the unknown?

Specific Heat Plan and Solve Replace each variable with its known value.

Specific Heat Plan and Solve Replace each variable with its known value.

Specific Heat Look Back and Check Is your answer reasonable?

Round off the data to give a quick estimate. Specific Heat Look Back and Check Is your answer reasonable? Round off the data to give a quick estimate. Q = 500 g × 0.5 J/g•°C × 100°C = 25 kJ This is close to 21.4 kJ, so the answer is reasonable.

Specific Heat A calorimeter is used to measure specific heat. A sample is heated and placed in the calorimeter. The temperature change is observed.

What is the thermal energy of an object? Assessment Questions What is the thermal energy of an object? the total number of atoms or molecules the total kinetic energy of the atoms or molecules the average kinetic energy of the atoms or molecules the average mechanical energy of the atoms or molecules

What is the thermal energy of an object? Assessment Questions What is the thermal energy of an object? the total number of atoms or molecules the total kinetic energy of the atoms or molecules the average kinetic energy of the atoms or molecules the average mechanical energy of the atoms or molecules ANS: B

What causes a gas to expand when its temperature is increased? Assessment Questions What causes a gas to expand when its temperature is increased? The number of particles increases as temperature increases. Each particle expands as its temperature increases, so the total volume increases. As temperature increases, more electrons leave atoms and move separately. As gas particles move faster, they overcome some forces of attraction.

What causes a gas to expand when its temperature is increased? Assessment Questions What causes a gas to expand when its temperature is increased? The number of particles increases as temperature increases. Each particle expands as its temperature increases, so the total volume increases. As temperature increases, more electrons leave atoms and move separately. As gas particles move faster, they overcome some forces of attraction. ANS: D

Assessment Questions The specific heat of water is 4.18 J/g•°C. How much heat is required to raise the temperature of 1,000 grams of water by 50°C? 83.6 J 83.6 kJ 209 J 209 kJ

Assessment Questions The specific heat of water is 4.18 J/g•°C. How much heat is required to raise the temperature of 1,000 grams of water by 50°C? 83.6 J 83.6 kJ 209 J 209 kJ ANS: D

What property of matter can be measured using a calorimeter? Assessment Questions What property of matter can be measured using a calorimeter? temperature thermal expansion specific heat mass

What property of matter can be measured using a calorimeter? Assessment Questions What property of matter can be measured using a calorimeter? temperature thermal expansion specific heat mass ANS: C

Assessment Questions Temperature is the transfer of thermal energy from one object to another. True False

Assessment Questions Temperature is the transfer of thermal energy from one object to another. True False ANS: F, Heat

Today’s special HW Check; Q & A Lab: Specific heat Lab due next time!

Today’s special Turn in lab on front table Notes II HW II due next time

Conductors

Insulators

Conduction, convection, radiation

Thermodynamics First Law of Thermodynamics Energy is conserved

Thermodynamics Second Law of Thermodynamics-Entropy

Thermodynamics Third Law of Thermodynamics 0 K cannot be reached

Assessment Questions What form of energy transfer requires the motion of particles of a fluid? conduction convection radiation insulation

Assessment Questions What form of energy transfer requires the motion of particles of a fluid? conduction convection radiation insulation ANS: B

What happens in every case in which energy is added to a system? Assessment Questions What happens in every case in which energy is added to a system? Temperature increases. Work is done on the system. All of the energy can be accounted for as work or heat. An identical amount of energy is removed from the system.

What happens in every case in which energy is added to a system? Assessment Questions What happens in every case in which energy is added to a system? Temperature increases. Work is done on the system. All of the energy can be accounted for as work or heat. An identical amount of energy is removed from the system. ANS: C

Thermal energy can move from a cooler object to a warmer object when Assessment Questions Thermal energy can move from a cooler object to a warmer object when the warmer object is larger. the cooler object has more thermal energy. energy is transferred by radiation. work is done on the system.

Thermal energy can move from a cooler object to a warmer object when Assessment Questions Thermal energy can move from a cooler object to a warmer object when the warmer object is larger. the cooler object has more thermal energy. energy is transferred by radiation. work is done on the system. ANS: D

According to the third law of thermodynamics, it is impossible Assessment Questions According to the third law of thermodynamics, it is impossible to cool an object to absolute zero. transfer thermal energy from a cooler object to a warmer object. convert energy from one form to another. account for all of the energy in a system.

According to the third law of thermodynamics, it is impossible Assessment Questions According to the third law of thermodynamics, it is impossible to cool an object to absolute zero. transfer thermal energy from a cooler object to a warmer object. convert energy from one form to another. account for all of the energy in a system. ANS: A

Assessment Questions All metals are good thermal insulators. True False

Assessment Questions All metals are good thermal insulators. True False ANS: F, conductors

History of the steam engine

Heat Engines When the valve in a steam engine slides, steam is trapped in the cylinder. The steam expands and cools as it pushes the piston to the left. Hot steam in Slide valve Exhaust steam out Valve rod Piston rod Cylinder Piston

Heat Engines Most cars have a four-stroke internal combustion engine. This diagram shows only one of the cylinders during each stroke. Intake valve Spark plug Exhaust valve Air-fuel mixture Cylinder Exhaust gases Piston Intake stroke Compression Stroke Power stroke Exhaust stroke

Heating Systems Thermostat Within the pipes of this hot-water heating system, the water circulates in a convection current. In each room, the air moves in a convection current. Radiator Exhaust vent Expansion tank Boiler Circulating pump

Forced air heating system. Heating Systems Forced air heating system. Hot air rises Cool air sinks Supply vent Return vent Chimney Duct Furnace

Cooling Systems In a window air conditioner, outside air is heated as a fan blows it through the condenser coil. Condenser coil Vapor cools to liquid as heat is removed. Warm air out Cold air out Compressor Expansion valve Pressure drops, causing liquid refrigerant to become cold. Warm air in Evaporator coil Liquid absorbs heat to become vapor.

Assessment Questions Only about one-third of the energy in gasoline is converted to work in an internal combustion engine. The rest of the chemical energy is lost as unused mechanical energy. destroyed by the engine. converted to potential energy. discharged as waste heat.

Assessment Questions Only about one-third of the energy in gasoline is converted to work in an internal combustion engine. The rest of the chemical energy is lost as unused mechanical energy. destroyed by the engine. converted to potential energy. discharged as waste heat. ANS: D

How is a room heated by an electric baseboard heating system? Assessment Questions How is a room heated by an electric baseboard heating system? conduction and convection only conduction and radiation only convection and radiation only conduction, convection, and radiation

How is a room heated by an electric baseboard heating system? Assessment Questions How is a room heated by an electric baseboard heating system? conduction and convection only conduction and radiation only convection and radiation only conduction, convection, and radiation ANS: C

How do air conditioners reverse the normal flow of heat? Assessment Questions How do air conditioners reverse the normal flow of heat? moving cool air from outside to inside the house separating warm atoms from cool atoms vaporizing and condensing a refrigerant blowing the warm air away with a fan

How do air conditioners reverse the normal flow of heat? Assessment Questions How do air conditioners reverse the normal flow of heat? moving cool air from outside to inside the house separating warm atoms from cool atoms vaporizing and condensing a refrigerant blowing the warm air away with a fan ANS: C

Assessment Questions Forced air heating systems are often used to heat many buildings from a central location. True False

Assessment Questions Forced air heating systems are often used to heat many buildings from a central location. True False ANS: F, Steam

Today’s special HW check; Q&A Happy Groundhog Day! Practice test The Cosmos Test next time! Feedback on papers

Today’s special Turn in Practice Test on front table Test 16; Answer MC questions in Smart Response Write sentences for each question and answer essays, then turn in test on front desk Work quietly on Vocab 20 and read chapter quietly until all have finished