# Document 10455540

Phy 2053 Announcements

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Exam 2 is coming soon!!

Thursday, April 2, 8:20 – 10:10 pm

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Material from Chapters 5-8 of Serway/Vuille

Only the sections we covered in class

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20 questions, multiple choice

Very much like the first exam

There is only one correct answer to the question “In order to receive credit for this problem, you must correctly code (“bubble in”) your UFID and your 5-digit test number…”

Æ I have correctly bubbled my UFID number and 5-digit test code.

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Please get there at least 10 minutes early, and preferably 20 minutes

New protocols - stay in your seat until your exam is collected. Raise your hands; proctors will come to collect it.

If you want to avoid the long wait at the end, either (a) come early and sit at the front or (b) finish early

More Phy 2053 Announcements

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Room assignments for Exam 2

BRY130: A-ELU

FLG220: EMM-HER

FLG230: HEW-LAI

FLG260: LAM-MON

FLG270: MOO-P

LIT121: R-SAW

MAEB211:SCH-T

MAT18: U-Z

You be allowed one handwritten formula sheet

(both sides), 8 ½” x 11” paper

In class review, Tuesday, March 31

Even More Phy 2053 Announcements

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Make-up exam for students missing Exams

1 and 2 will be held Wednesday, April 22 from 7:20 – 9:10 pm

Room to be announced later

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If you need to take a make-up because of a legitimate excuse, please send Prof. Chan and I an e-mail as soon as possible

HW Assignment 9 due two weeks from yesterday, Wednesday, March 8

But, you should do the problems from Ch 8 before the test!

Rotational Kinetic Energy

Equivalent to

KE =

KE

=

1

2

1

2

I

### ω

m v 2

2

Conservation of Mechanical Energy

( KE t

+ KE r

+ PE g

+ PE ) = ( KE t

+ KE r

+ PE g

+ PE

Work-Energy Theorem: W nc

=

Δ

KE t

+

Δ

KE

R

+

Δ

PE

Example: Problem 8-44, p 262

Four objects – a hoop, a solid cylinder, a solid sphere, and a thin, spherical shell – each have a mass of 4.8 kg and a radius of 0.23 m. (a) Find the moment of inertia for each object as it rotates about the axes shown in Table

8.1. (b) Suppose each object rolls down a ramp without slipping. Rank the translational speed of each object from highest to lowest. (c) Rank the objects’ rotational kinetic energy from highest to lowest as the objects roll down the ramp.

θ http://www.photoshopsupport.com/photoshop-blog

/05/10/11-liquid-sculpture.html

http://p25ext.lanl.gov/~hubert/aerogel/

### Solids and Fluids

www.pbs.org/wgbh/nova/volcano/anat_02.html

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### States of Matter

Solid

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Atoms close together

Fixed positions

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Electrostatic forces

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Quantum mechanics!

I - crystalline

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Liquid

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No long range order

(usually) at higher

Temperatures

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Gas

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Molecules are in constant random motion

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Molecules exert weak forces on each other

Average separation is large compared to the size of the molecules

Plasma

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Gas heated to a very high temperature

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Many of the electrons are freed from the nucleus

II - amorphous

### States of matter – what we don’t know

What the universe is made of:

?

?

### Elastic Properties of Solids

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Stress is the force per unit area causing the deformation

Strain is a measure of the amount of deformation

The elastic modulus is the constant of proportionality between stress and strain

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For sufficiently small stresses, the stress is directly proportional to the strain

The constant of proportionality depends on the material being deformed and the nature of the deformation

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Quantitative characterization of mechanical properties of materials

Elastic behavior:

Hooke’s Law

A

L

0

Δ

L

F

Stress = F/A

Strain =

Δ

L/L

0

F

A

Y

L

L o

or

=

3