+ All Categories
Home > Documents > What is Temperature? Take 5 minutes to talk to your lab partner. Answer the following questionsTake...

What is Temperature? Take 5 minutes to talk to your lab partner. Answer the following questionsTake...

Date post: 23-Dec-2015
Category:
Upload: damon-curtis
View: 220 times
Download: 4 times
Share this document with a friend
Popular Tags:
16
What is Temperature? What is Temperature? Take 5 minutes to talk to your Take 5 minutes to talk to your lab partner. Answer the lab partner. Answer the following questions following questions What is temperature? What is temperature? How do you decide what temperature How do you decide what temperature something is? something is? How hot is hot? How cold is cold? How hot is hot? How cold is cold? When we say something is hot or When we say something is hot or cold, is that a qualitative measure cold, is that a qualitative measure or a quantitative measure? or a quantitative measure? When we say something is 50 degrees When we say something is 50 degrees Celsius is that a qualitative Celsius is that a qualitative measure or a quantitative measure? measure or a quantitative measure?
Transcript

What is Temperature?What is Temperature?

• Take 5 minutes to talk to your lab Take 5 minutes to talk to your lab partner. Answer the following questionspartner. Answer the following questions– What is temperature? What is temperature? – How do you decide what temperature How do you decide what temperature

something is?something is?– How hot is hot? How cold is cold?How hot is hot? How cold is cold?– When we say something is hot or cold, is When we say something is hot or cold, is

that a qualitative measure or a quantitative that a qualitative measure or a quantitative measure?measure?

– When we say something is 50 degrees When we say something is 50 degrees Celsius is that a qualitative measure or a Celsius is that a qualitative measure or a quantitative measure?quantitative measure?

Kinetic EnergyKinetic Energy

• Temperature is the measure of the Temperature is the measure of the average kinetic energy of particles.average kinetic energy of particles.– Temperature is NOT a measure of heat.Temperature is NOT a measure of heat.

• We already know that kinetic energy is We already know that kinetic energy is another way to talk about the amount of another way to talk about the amount of movement of particles. SO…. movement of particles. SO….

Higher temperature = More kinetic energyHigher temperature = More kinetic energy

How Do How Do Thermometers Work?Thermometers Work?

• Liquid thermometers work because of Liquid thermometers work because of thermal expansionthermal expansion. Thermal . Thermal expansion is the increase of volume expansion is the increase of volume of a substance due to an increase in of a substance due to an increase in temperature.temperature.

• Many thermometers use either Many thermometers use either mercurymercury or or alcoholalcohol because they because they remain in the liquid form over a large remain in the liquid form over a large range of temperatures.range of temperatures.

How Do How Do Thermometers Work?Thermometers Work?

• When a thermometer is placed in hot When a thermometer is placed in hot water bath, heat energy transfers from the water bath, heat energy transfers from the hot water bath to the thermometer. The hot water bath to the thermometer. The temperature reading on the thermometer temperature reading on the thermometer rises. It continues to rise until the kinetic rises. It continues to rise until the kinetic energy of the particles in the thermometer energy of the particles in the thermometer match the kinetic energy of the particles in match the kinetic energy of the particles in the hot water.the hot water.

Who invented the Who invented the thermometer?thermometer?

Galileo- in 1596Galileo- in 1596

Thermal EnergyThermal EnergyHeat TransferHeat Transfer

Thermal energy is the internal energy Thermal energy is the internal energy in substances. It is vibration and in substances. It is vibration and

movement of atoms and molecules movement of atoms and molecules within substances.within substances.

ConvectionConvection• the transfer of heat (thermal the transfer of heat (thermal

energy) by the actual movement energy) by the actual movement of the warmed matter. It most of the warmed matter. It most frequently occurs in gases or frequently occurs in gases or liquids.liquids.

• Heat leaves the coffee cup as Heat leaves the coffee cup as the currents of steam and air the currents of steam and air rise. rise.

• The heat moves with the fluid. The heat moves with the fluid.

Consider ThisConsider This

• Convection is responsible for making Convection is responsible for making macaroni rise and fall in a pot of heated macaroni rise and fall in a pot of heated water. The warmer portions of the water water. The warmer portions of the water are less dense and therefore, they rise. are less dense and therefore, they rise. Meanwhile, the cooler portions of the Meanwhile, the cooler portions of the water fall because they are denser.water fall because they are denser.

ConductionConduction• the transfer of energy through the transfer of energy through

matter from particle to particle. It is matter from particle to particle. It is the transfer and distribution of heat the transfer and distribution of heat energy from atom to atom within a energy from atom to atom within a substance. It is most effective in substance. It is most effective in solids-but it can happen in fluids. solids-but it can happen in fluids.

• It is simplyIt is simply the transfer of thermal the transfer of thermal energy through direct contact.energy through direct contact.

• For example, a spoon in a cup of For example, a spoon in a cup of hot soup becomes warmer hot soup becomes warmer because the heat from the soup is because the heat from the soup is conducted along the spoon. conducted along the spoon.

Fun FactFun Fact

• Have you ever noticed that metals tend to Have you ever noticed that metals tend to feel cold? Believe it or not, they are not feel cold? Believe it or not, they are not colder! They only feel colder because they colder! They only feel colder because they conduct heat away from your hand. You conduct heat away from your hand. You perceive the heat that is leaving your hand perceive the heat that is leaving your hand as cold. as cold.

Do these items look familiar?Do these items look familiar?

What do they have in What do they have in common?common?

What do they have in What do they have in common?common?

• All the items in the previous slide are All the items in the previous slide are insulatorsinsulators. . An insulator is a substance that does not An insulator is a substance that does not conduct thermal energy well and reduces the conduct thermal energy well and reduces the amount of heat transfer.amount of heat transfer.

• Substances that DO conduct thermal energy Substances that DO conduct thermal energy well are called well are called conductorsconductors..

• Take a few minutes to brainstorm a lists some Take a few minutes to brainstorm a lists some common (household) conductors and insulators common (household) conductors and insulators with your lab partner…with your lab partner…

Radiation Radiation • Electromagnetic waves that Electromagnetic waves that

directly transport ENERGY directly transport ENERGY through space.through space.

• Sunlight is a form of radiation. Sunlight is a form of radiation. The thermal energy of the sun is The thermal energy of the sun is radiated through space to our radiated through space to our planet without the aid of fluids or planet without the aid of fluids or solids. The energy travels solids. The energy travels through nothingness! through nothingness!

• Just think of it! The sun transfers Just think of it! The sun transfers heat through 93 million miles of heat through 93 million miles of space. space.

How do we know it’s radiation?How do we know it’s radiation?

BECAUSE…..BECAUSE….. • There are no solids (like a huge spoon) There are no solids (like a huge spoon)

touching the sun and our planet, touching the sun and our planet, conduction is not responsible for bringing conduction is not responsible for bringing heat to Earth. heat to Earth.

• Since there are no fluids (like air and Since there are no fluids (like air and water) in space, convection is not water) in space, convection is not responsible for transferring the heat.responsible for transferring the heat.

How a radiometer worksHow a radiometer works• Heat excites the black surface of Heat excites the black surface of

the vanes more than it heats the the vanes more than it heats the white surface. Black absorbs more white surface. Black absorbs more thermal energy it is considered a thermal energy it is considered a good radiator. good radiator.

• The difference in temperature The difference in temperature between the warm, black side and between the warm, black side and the cooler white side causes the cooler white side causes gasses to creep along the surface gasses to creep along the surface of the vanes. This effect is known of the vanes. This effect is known as "thermal creep." The faster as "thermal creep." The faster gasses from the black side strike gasses from the black side strike the edges of the vane at an angle the edges of the vane at an angle with more force than the molecules with more force than the molecules from the cold side. The equal and from the cold side. The equal and opposite forces cause the opposite forces cause the radiometer to spin. radiometer to spin.


Recommended