Physics 7A Section C, D Lecturer Dr. Yu Sato Lecture slides available at .

Physics 7ASection C, D

Lecturer Dr. Yu Sato

• Lecture slides available athttp://physics7.ucdavis.edu

http://physics7.ucdavis.edu/

http://physics7.ucdavis.edu/

Course Websitehttp://physics7.ucdavis.edu

Click on Physics 7A-C/D

Course Policy Highlights

Text College Physics: A Models Approach, Part I by W. PotterTextDiscussion/Lab Workbook

Final Examination March 18, Tuesday, 10:30am –12:30pm

Course Grading = Exam grade +/- DL grade.

Exam grade (8 quizzes and the final)D/L grade

Your quiz grade is the average of seven highest individual quiz grades. Your Exam grade is then the higher of either of the two weighting schemes.

(a) 50% Quiz grade + 50% Final grade(b) 20%Quiz grade + 80% Final grade

Eight Quizzes during lecturesGo to your assigned lecture time

Q R S T

We need the red circled boxes to identify youThe blue circled boxes helps us sort and enter results,

getting them back to you fasterWe categorise/grade your responses based on :

(1) your understanding of the problem(2) choice of appropriate model(3) logic to arrive at the (hopefully correct) answer.

To find out the meaning of each of the letters, look on the website.

Attendance in the DL(Discussion/Lab) section is

MANDATORY

Academic Dishonesty• Copying during quizzes/exams.• Taking a test for another student.• Modifying a quiz before asking for a re-grade.

• DLs start immediately after lecture.

• All DLs are in 168 Roessler (i.e. upstairs)

First DL starts TODAY

IMPORTANTAll people who are wait-listed or not enrolled in the DL:

Do not join a table or go up to the TA immediately. Collect in a corner, allow the TA to get the lab started

and then the TA will address wait-list and enrollment issues.

What is physics?Why is the sky blue?

What is “rainbow” really?

How does a lightswitch work?

Why does she start spinning so much faster when she pulls her arms and legs in? How do planes fly?

How do magnets work?

Can ice be colder than 0°C?

We begin with the child-like wonder about our everyday world.

What does a physicist do?

Ouch…Umm why does an apple fall ??How far does the power of gravity extend??What does apple’s fall to do with celestial motion?

Sir. Isaac Newton

Physicists...• they observe phenomena and ask questions

about them• Try to explain phenomena using a few

principles (models) - You cannot “pick and choose” when an

explanation works- you must have understanding of when

a model is valid and when it is not.

Physics is taking this approach to explain phenomena in the physical world.

Models…

What is physics 7?

Discussion/Lab

lectureQuiz & Final Text

It will require your active participation! (DL grade will reflect this.)

What is physics 7?Physics 7 is a 3-quarter series of physics classes, typically taken by bio-science and other non-physical science majors.

• Physics 7A: Energy conservation, thermodynamics, particle models of matter. • Physics 7B: Classical Mechanics, rotational motion, fluids, circuits. • Physics 7C: Wave phenomena, optics, electricity and magnetism, the atom and modern quantum mechanics.

ModelsUseful way to think of and address

questions about phenomena(e.g. Ideal gas model)

Models in Physics 7AModels can help us organize our thinking,

can contain other models, and can be very useful. Models also have limitations: experiment is the final judge.

• Three-phase model of matter

• Energy-interaction model

• Mass-spring oscillator• Particle model of matter

Particle model of bond energy Particle model of thermal energy

• Thermodynamics• Ideal gas model• Statistical model of thermodynamics

We start withThese two…

Three-Phase model of Matter

• Solid: Keeps its shape without a container• Liquid: Takes the shape of the (bottom of)

the container. Keeps its volume the same.• Gas: Takes the shape and volume of the

container.

Example H2O


Q How do we change the phase of matter?

How do we change the temperature of matter?

A By adding or removing energy. Often this energy is transferred from, or to the substance as heat Q.

Example H2O


• At constant pressure, changes of phase occur at specific temperatures.

• The phase change temperatures (TMP, TBP) are the same going through the phase change in both directions.

• The amount of energy added/removed at a phase change (∆HM:Heat of melting, ∆HV:Heat of vaporization) is unique to each substance.

Example Melting ice

Temperature

Energy added or removed

liquid

gas

l-g coexist

s-l coexist

TMP

TBP


solid

Melting iceTi= 20°C => Tf = room temperature

Temperature

Energy of substance

solid

liquid

gas

l-g coexist

s-l coexist

TMP

TBP

Melting ice

Temperature

Energy of substance

solid

liquid

gas

l-g coexist

s-l coexist

Initial

TMP

TBP

Final

Energy systems:There are many different types of energies called energy

systems:

EEthermatherma

ll

EEbondbondEEmovementmovement

(KE)(KE)

EEgravitgravit

yy

EEelectrielectri

cc

EEsprinsprin

gg

........

For each energy system, there is an indicator that tells us how that energy system can change.

Ethermal: indicator is temperatureEbond: indicator is the initial and final phases

Energy-Interaction Model

Let’s talk about Conservation of EnergyLet’s talk about Conservation of Energy• Energy is both a thing (quantity) and a process. You & I contain energy, as do the chairs you sit on and the air we breathe. • We cannot see it, but we can measure the transformation of energy (or change, E).

Conservation of EnergyEnergy cannot be created nor destroyed, simply

converted from one form to another.

• If the energy of an object increases, something else must have given that object its energy.

• If it decreases, it has given its energy to something else. Energy transfer is done through Heat or Work.

Energy Interaction DiagramsBased on the energy interaction model, it shows you how energy is transferred,

how energy is conserved between energy systems.

Energy interaction diagrams - closed

EEaa EEbb EEcc

Conservation of EnergyThe total energy of a closed physical system must remain constant. In other words, the change of the energies of allenergy systems associated with the physical system must sum to zero.

Change in system energy = ∆Ea + ∆ Eb + ∆ Ec = 0

€€

Energy interaction diagrams - open

EEaa EEbb EEcc

Conservation of EnergyThe change of the energies of all energy systems associated with an open physical system must sum to the net energy added/removed as heat or work.

Change in system energy = ∆Ea + ∆ Eb + ∆ Ec

= (Energy added) - (Energy removed) = Q+W

€€Energy added Energy removed

Energy interaction diagramsExample Melting iceTi= 0°C => Tf = room temperature

Temperature

Energy of substance

solid

liquid

gas

l-g coexist

s-l coexist

Initial

TMP

TBP

Final

Energy interaction diagramsExample Melting ice

Process 1 : Ice at T= 0°C => Water at T = 0°C Process 2 : Water at T = 0°C => Water at room temperature

Temperature

Energy of substance

solid

liquid

gas

l-g coexist

s-l coexist

Process1Initial

TMP

Process1

Final=

Process2

initial

Process2Final

Energy-Interaction ModelExample Melting ice

Ice

Process 1 : Ice at T= 0°C => Water at T = 0°C

∆T=0

∆Eth=0

Initial phase Solid, Final phase Liquid

EEthermtherm

alalEEbondbond


Ice


∆T=0

∆Eth=0


HeatEEthermtherm

alalEEbondbond

EEthermtherm

alalEEbondbond


Ice


∆T=0

∆Eth=0


∆Eth + ∆Ebond= Q+W

∆Ebond= Q

Heat

EEthermtherm

alalEEbondbond


Ice

Process 2 : Water at T = 0°C => Water at room temperature

Initial phase Liquid, Final phase Liquid

EEthermtherm

alalEEbondbond


Ice



∆Ebond= 0

T

EEthermtherm

alalEEbondbond


Ice



∆Ebond= 0

Heat

T

∆Eth + ∆Ebond= Q+W

∆Eth= Q

EEthermtherm

alalEEbondbond


Freezing

Ice

∆T=0

∆Eth=0

Initial phase Liquid, Final phase Solid

(Ice at T= 0°C <= Water at T = 0°C)

EEthermtherm

alalEEbondbond


Freezing

Ice

∆T=0

∆Eth=0


Heat

(Ice at T= 0°C <= Water at T = 0°C)

Next lecture Jan 15

Quiz 2 will cover today’s lecture, Discussion/Lab 1 material

INCLUDING FNT(For Next Time) questions.

Physics 7A Section C, D Lecturer Dr. Yu Sato Lecture slides available at .

Documents