Heat- is the transfer or flow of thermal energy between objects that have different temperatures. -Heat moves from substances that are warmer ( more thermal e.) to colder substances(less Th. E)

Heat and temperature

PLS. COPY THIS TO YOUR NOTES!!!!

• Thermal energy: the total KE and PE of the particles in a substance ( s, l or gas ). The more particles there are, the MORE thermal energy.

The greater the average distance between particles, the greater the potential energy of the particles.

MORE MASS = MORE TH. E.If KE is the same, the thermal E. can be different b/c

the PE of the particles can be different.

• Temperature—measure of the average kinetic energy (speed )of the molecules in a material.(how fast or slow they are going)

• Thermometer- instrument to measure temperature.

The potential energy of the soccer ball depends on the distance between the ball and Earth. The potential energy of the particles of matter depends on their distance from one another.

Lesson 1 – LR2

A. different thermal energiesB. different temperaturesC. different kinetic energiesD. the same thermal energy

Particles that make up liquid and solid water have different potential energies, and therefore also have which of the following?

Now, can you do this?

KE is to ____________________ as

PE and KE is to _______________________

http://www.youtube.com/watch?v=f1eAOygDP5s

Bill nye on Heat

Temperature SCALES CELSIUS KELVIN FAHRENHEITBP 100 373 212 FP 0 273 32 AZ –273 0 -460 (ADD 273 TO GET k) (-273 TO GET C)

BP= boiling pointFP= freezing pointAZ = absolute zero

Absolute Zero– point at which an object has almost no energy in it. Has not been reached yet…

Have we reached it? No, not yet, however MIT has come ridiculously close (within one nanokelvin or .00000000001K of it)Source(s):https://www.youtube.com/watch?v=TNUDBdv3jWIAt some level, there is always some heat being released,keeping us from reaching it.

Temperature conversions !!! How do we convert ºC to K?

• K = ºC +273

200 °C = ______? K

• How do we convert K to ºC

ºC = K - 273

Problem:

Problem: 105 K = ? ºC

Temperature conversions !!!

• How do we change ºF to ºC ?

• ºC = 5/9 (ºF – 32 )

• or, (ºF – 32 )

1.8How do we change ºC to ºF ?

ºF = ( 9/5 x ºC) + 32 or, (ºC x 1.8) + 32

Problem:

98.6 ºF ______ ? °C

Problem:

30 ºC = ? ºF

Temperature conversion problems to do: Just do the ones that are circled in red; do degrees Celsius and Kelvin problems first….1. 75 °F = __________ °C

2. 0 °F =__________ °C

3. 98.6 °F __________ °C 4. -10 °F =__________ °C

5. 45 °C = __________ °F

6. 30 °C = __________ °F

7. -10 °C = ___________ K 8. 200 °C = __________ K9. 40 K = __________ °C 10. 37 C = ? F11. 86 F = ? K12. 473 K = ? C = ? F

Temp. answers

1.75 °F = __23.9____ °C

2.0 °F = _ -17.8____ °C

3.98.6 °F = _ 37_____ °C

4.-10 °F = _-23.3___ °C 5.45 °C = __113____ °F

6.30 °C = __86_____ °F 7.-10 °C = __263___ K

8.200 °C = _473_____ K9. 40 K = _ 233____ °C

Units used to measure Thermal Energy ( Heat moves it )

• Heat is measured in units called Calories or Joules (J)• One calorie is the amount of heat needed toraise 1 ml(g) of water by 1 degree Celsius.

      Related Topics

A calorie is a unit of energy. We tend to associate calories with foodbut they apply to anything containing energy. For example, a gallon (about 4 liters) of gasoline contains about 31,000,000 calories.•Specifically, a calorie is the amount of energy, or heat, it takes to raise the temperature of 1 gram of water 1 degree Celsius (1.8 degrees Fahrenheit).• One calorie is equal to 4.186 joules, a common unit of energy used in the physical sciences.

Most of us think of calories in relation to food, as in "This can of soda has 200 calories.“ It turns out that the calories on a food package are actually kilocalories (1,000 calories = 1 kilocalorie). The word is sometimes capitalized to show the difference, but usually not. A food calorie contains 4,184 joules.

A can of soda containing 200 food calories contains 200,000 regular calories, or 200 kilocalories.

A gallon of gasoline contains 31,000 kilocalories.

The same applies to exercise -- when a fitness chart says you burn about 100 calories for every mile you jog, it means 100 kilocalories. For the duration of this conversation, when we say "calorie," we mean "kilocalorie."

The JOULE is the SI unit used to measure the amount of thermal energy. Developed by James Joule. 1 calorie = 4.19 J. 1 kilocalorie = 4,186 J England and other countries in Europe use the BTU. (1 calorie = .00397 Btu’s. ;  1 Btu = 1,055 joules. 1 Btu = .252 kilocalories (kcal) )

Heat Transfer- Use smart bd slide show alsomovement of thermal energy from a warmer substance to a cooler substance.

There are 3 ways in which heat transfer takes place: conduction, convection and radiation

Video on heat transfer

• http://studyjams.scholastic.com/studyjams/jams/science/energy-light-sound/heat.htm

Convection simulation---A blob of potassium

permanganate shows convection currents in a beaker

of water as it is heated• http://www.youtube.com/watch?

v=a3BdBiSmlFU&feature=related

1. Convection: Heat is transferred in liquids and gases

through movement of particles from one area of a liquid or gas (fluids)to another by up and down movements, called Convection Currents.

This cycle of cooler water sinking and forcing warmer water upward is an example of convection.

Convection Currents in Earth’s Atmosphere

2. Conduction: heat is transferred through a substance, or from 1 to the other by direct contact of molecules.

This mostly takes place in solids, and liquids

Conduction simulation:

http://www.youtube.com/watch?v=-UcBRveX_78&feature=relatedhttp://www.youtube.com/watch?v=-UcBRveX_78&feature=related

Calorimeter—a device that measures heat gain from 1 substance to the other. via conduction

Thermal Insulators--- do not conduct thermal energy or electricity well; keep things warm or cool Ex: thermos, wood, plastic, comforter, styrofoam, air, glass

Thermal Conductors: allow thermal energy and electricity to flow through them; ex: metals, water ,air, glass

3. Radiation: thermal energy is transferred through empty space by electromagnetic waves. No matter is needed.

Review of thermal energy transfer

http://www.teachersdomain.org/asset/lsps07_int_heattransfer/

Thermal Expansion: •Increase in volume ( size ) of a substance, caused by absorption of thermal energy as heat moves it.

Contraction: •decrease in volume ( size ) due to loss of thermal energy

• Thermal contraction and expansion:

When materials are heated, they expand, and when cooled they contract. That is why you see expansion joints (pictured below) on bridges and parking ramps. That is on reason sidewalks and roadways split too.The degree of expansion or contraction depends on the material.

One other interesting thing: when cooled, water will contract until it reaches a certain temperature, and then it actually starts to expand. This effect is what keeps ice on top of lakes.

                                                                           

Thermostat: device that controls temperature with a bimetallic strip .

Bimetallic strip: switch in a thermostat .

Which has more thermal energy – a bucket of water at 50

degrees C or a cup of boiling water at 100 degrees C ?

The amount of thermal energy a substance has depends on the MASS of the substance, AND the motion of the molecules!!!

Ex: 10 g of H₂O @ 90 degrees F is hotter or colder than 5 g H ₂O @ 90 degrees F?

Problem: if it takes 1 calorie to raise 1 ml (g, cc) ofWater 1 degree—1. how many calories would it take to Raise 500 mL of water 2 degrees, if it was at 40 degrees Celsius?

2. How many calories are needed to change 30 grams of ice into water? ( HINT: it takes 80 calories to melt 1 g)

Specific Heat---water has a HIGH specific heat

Ability of a substance to absorb thermal energy.

The specific heat of water is :(1 cal/g/C) ; OR, 4,186J/kg/degrees C

COPY: WATER HAS THE HIGHEST SPECIFIC HEAT OF ANY LIQUID ON EARTH !

Specific heat of some substances

• When a material has a low specific heat, transferring a small amount of thermal energy to the material increases its temperature significantly.

• Thermal energy can be transferred through radiation, conduction, or convection.

• When a material is heated, the thermal energy of the material increases and the material expands.

Lesson 2 – LR1

A. convection currentB. specific heatC. thermal conductor D. thermal insulator

Which term refers to a material through which thermal energy flows easily?

Lesson 2 – LR3

A. convectionB. conductionC. thermal contraction D. thermal expansion

What term describes the transfer of thermal energy by the movement of particles from one part of a material to another?

Lesson 2 – LR2

A. conductionB. thermal expansionC. thermal conductor D. thermal contraction

Which describes an increase in a material’s volume when its temperature increases?