Temperature Introduction Section 0 Lecture 1 Slide 1 Lecture 22 Slide 1 INTRODUCTION TO Modern Physics PHYX 2710 Fall 2004 Physics of Technology—PHYS 1800

Temperature

Introduction Section 0 Lecture 1 Slide 1

Lecture 22 Slide 1

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Physics of Technology

PHYS 1800

Lecture 22

Temperature

Temperature


Lecture 22 Slide 2


Fall 2004


Spring 2009

PHYSICS OF TECHNOLOGY Spring 2009 Assignment Sheet

*Homework Handout

PHYSICS OF TECHNOLOGY - PHYS 1800 ASSIGNMENT SHEET

Spring 2009 Date Day Lecture Chapter Homework Due Feb 16 17 18 19 20

M Tu W H F*

Presidents Day Angular Momentum (Virtual Monday) Review Test 2 Static Fluids, Pressure

No Class 8 5-8 5-8 9

-

Feb 23 25 27

M W F*

Flotation Fluids in Motion Temperature and Heat

9 9 10

6

Mar 2 4 6

M W F*

First Law of Thermodynamics Heat flow and Greenhouse Effect Climate Change

10 10 -

7

Mar 9-13 M-F Spring Break No Classes Mar 16 18 20

M W F*

Heat Engines Power and Refrigeration Electric Charge

11 11 12

8

Mar 23 25 26 27

M W H F*

Electric Fields and Electric Potential Review Test 3 Electric Circuits

12 13 9-12 13

-

Mar 30 Apr 1 3

M W F

Magnetic Force Review Electromagnets Motors and Generators

14 9-12 14

9

Apr 6 8 10

M W F*

Making Waves Sound Waves E-M Waves, Light and Color

15 15 16

10

Apr 13 15 17

M W F*

Mirrors and Reflections Refraction and Lenses Telescopes and Microscopes

17 17 17

11

Apr 20 22 24

M W F

Review Seeing Atoms The really BIG & the really small

1-17 18 (not on test) 21 (not on test)

No test week 12

May 1 F Final Exam: 09:30-11:20am * = Homework Handout

Temperature


Lecture 22 Slide 3


Fall 2004


Spring 2009


PHYS 1800

Lecture 19

Temperature

Temperature on an Atomic Scale

Temperature


Lecture 22 Slide 4


Fall 2004


Spring 2009

Describing Motion and InteractionsPosition—where you are in space (L or meter)

Velocity—how fast position is changing with time (LT-1 or m/s)

Acceleration—how fast velocity is changing with time (LT-2 or m/s2)

Force— what is required to change to motion of a body (MLT-2 or kg-m/s2 or N)

Inertia (mass)— a measure of the force needed to change the motion of a body (M)

Energy—the potential for an object to do work. (ML2T-2 or kg m2/s2 or N-m or J)

Work is equal to the force applied times the distance moved. W = F dKinetic Energy is the energy associated with an object’s motion. KE=½ mv2

Potential Energy is the energy associated with an objects position.Gravitational potential energy PEgravity=mghSpring potential energy PEapring= -kx

Momentum— the potential of an object to induce motion in another object (MLT -1 or kg-m/s)

Angular Momentum and Rotational Energy— the equivalent constants of motion for rotation (MT-1 or kg/s) and (MLT-2 or kg m/s2 or N)

Pressure— force divided by the area over which the force is applied (ML -1T-1 or kg/m-s or N/m2 or Pa)

Temperature


Lecture 22 Slide 5


Fall 2004


Spring 2009

Dennison’s Laws Thermal Poker(or How to Get a Hot Hand in Physics)

• 0th Law: Full House beats Two Pairs

• 1st Law: We’re playing the same game (but with a wild card)

• 2nd Law: You can’t win in Vegas.

• 3rd Law: In fact, you always loose.

• 0th Law: Defines Temperature

• 1st Law: Conservation of Energy (with heat)

• 2nd Law: You can’t recover all heat losses (or defining entropy)

• 3rd Law: You can never get to absolute 0.

Temperature


Lecture 22 Slide 6


Fall 2004


Spring 2009

• What is heat?• What is the relationship between quantity of heat

and temperature?• What happens to a body (solid, liquid, gas) when

thermal energy is added or removed?

Thermal Energy

Heat

Solid: Atoms vibrating in all directions about their fixed equilibrium (lattice) positions. Atoms constantly colliding with each other.

Liquid: Atoms still oscillating and colliding with each other but they are free to move so that the long range order (shape) of body is lost.

Gas: No equilibrium position, no oscillations, atoms are free and move in perpetual high-speed “zig-zag” dance punctuated by collisions.

gas

liquid

solid

Temperature


Lecture 22 Slide 7


Fall 2004


Spring 2009

++

+

++

+

++

+

Heat

221 mvTkB

kB is Boltzmann’s constant

=1.38 10-23 J/K

Temperature


Lecture 22 Slide 8


Fall 2004


Spring 2009


PHYS 1800

Lecture 19

Temperature

Measuring Temperature(0th Law of Thermodynamics)

Temperature


Lecture 22 Slide 9


Fall 2004


Spring 2009

What is Temperature?

• If two objects are in contact with one another long enough, the two objects have the same temperature.

• This begins to define temperature, by defining when two objects have the same temperature.– When the physical properties are no longer changing,

the objects are said to be in thermal equilibrium.– Two or more objects in thermal equilibrium have the

same temperature.– This is the zeroth law of thermodynamics.

– Corollary: Heat flows from hot to cold (DUH!!!)

Temperature


Lecture 22 Slide 10


Fall 2004


Spring 2009

• When two objects at different temperatures are placed in contact, heat will flow from the object with the higher temperature to the object with the lower temperature.

• Heat added increases temperature, and heat removed decreases temperature.

• Heat and temperature are not the same.

• Temperature is a quantity that tells us which direction the heat will flow.

Heat is a form of energy.(Here comes conservation of energy!!!)

Temperature and Heat

Temperature


Lecture 22 Slide 11


Fall 2004


Spring 2009

• The first widely used temperature scale was devised by Gabriel Fahrenheit.

• Another widely used scale was devised by Anders Celsius.

• The Celsius degree is larger than the Fahrenheit degree: the ratio of Fahrenheit degrees to Celsius degrees is 180/100, or 9/5.

• They are both equal at -40.

325

9

329

5

CF

FC

TT

TT

Temperature


Lecture 22 Slide 12


Fall 2004


Spring 2009

0 K Absolute zero -273.15 ºC

4.25 Liquid He boils -268.9

20.4 Liquid H boils -253

77 Liquid N2 boils -196

90 Liquid O2 boils -183

194 CO2 (dry ice) freezes -79

273 Water freezes 0

310 Body temperature ~ 37

1336 Gold melts 1063

5773 Carbon arc 5500

6273 Sun’s photosphere 6000

6293 Iron Welding arc 6020

Temperature Ranges

Temperature


Lecture 22 Slide 13


Fall 2004


Spring 2009

Temperature


Lecture 22 Slide 14


Fall 2004


Spring 2009

• The zero point on the Fahrenheit scale was based on the temperature of a mixture of salt and ice in a saturated salt solution.

• The zero point on the Celsius scale is the freezing point of water.

• Both scales go below zero.• Is there such a thing as

absolute zero?

Temperature


Lecture 22 Slide 15


Fall 2004


Spring 2009

What is absolute zero?

• If the volume of a gas is kept constant while the temperature is increased, the pressure will increase.

• This can be used as a means of measuring temperature.

• A constant-volume gas thermometer allows the pressure to change with temperature while the volume is held constant.

• The difference in height of the two mercury columns is proportional to the pressure.

Temperature


Lecture 22 Slide 16


Fall 2004


Spring 2009

• We can then plot the pressure of a gas as a function of the temperature.

• The curves for different gases or amounts are all straight lines.• When these lines are extended backward to zero pressure, they

all intersect at the same temperature, -273.2C.• Since negative pressure has no meaning, this suggests that the

temperature can never get lower than -273.2C, or 0 K (kelvin).

TK TC 273.2

Absolute zero

Temperature


Lecture 22 Slide 17


Fall 2004


Spring 2009

• Can anything ever get colder than 0 K?• No.

• Can absolute zero ever be reached?• No.

TK TC 273.2

Absolute zero and the 3rd Law of Thermodynamics

Temperature


Lecture 22 Slide 18


Fall 2004


Spring 2009


Next Lab/Demo: Fluid Dynamics TemperatureThursday 1:30-2:45

ESLC 46 Ch 9 and 10

Next Class: Wednesday 10:30-11:20

BUS 318 roomReview Ch 10

Documents

Temperature Introduction Section 0 Lecture 1 Slide 1 Lecture 22 Slide 1 INTRODUCTION TO Modern Physics PHYX 2710 Fall 2004 Physics of Technology—PHYS 1800