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12/05/2013 PHY 113 C  Fall 2013 -- Lecture 26 12/05/2013 PHY 113 C  Fall 2013 -- Lecture 26

12/05/2013 PHY 113 C Fall 2013 -- Lecture 26 - PowerPoint Presentation

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12/05/2013 PHY 113 C Fall 2013 -- Lecture 26 - PPT Presentation

1 PHY 113 C General Physics I 11 AM 1215 P M MWF Olin 101 Plan for Lecture 26 Comments on preparing for Final Exam Comprehensive review Part II Course assessment 12052013 PHY 113 C Fall 2013 Lecture 26 ID: 658079

phy 2013 lecture 113 2013 phy 113 lecture fall energy questions motion circular exam determine concepts final review force question problem ball

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Slide1

12/05/2013

PHY 113 C Fall 2013 -- Lecture 26

1

PHY 113 C General Physics I

11 AM – 12:15

P

M MWF Olin 101

Plan for Lecture 26:

Comments on preparing for Final Exam

Comprehensive review – Part II

Course

assessmentSlide2

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PHY 113 C Fall 2013 -- Lecture 26

2Slide3

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PHY 113 C Fall 2013 -- Lecture 26

3

Final exam schedule for PHY 113 CSlide4

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PHY 113 C Fall 2013 -- Lecture 26

4

Comments on Final Exam

It will be comprehensive (covering material from Chapters 1-22)

It is scheduled for 9 AM Dec. 12

th

in Olin 101

In class format

only

; no time pressure

May bring

4

equation sheets

Format will be similar to previous exams; may see problems similar to those on previous exams Slide5

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5

General advice on how to prepare for Final Exam

Review fundamental concepts and their corresponding equations

Develop equation sheets that help you solve example problems on all of the material. (You can assume that empirical constants and parameters will be given to you; they need not take up space on your equation sheet.)

Practice problem solving techniques.

If you find mysteries, unanswered questions, etc., please contact me.Slide6

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Problem solving steps

Visualize problem – labeling variables

Determine which basic physical principle(s) apply

Write down the appropriate equations using the variables defined in step 1.

Check whether you have the correct amount of information to solve the problem (same number of knowns and unknowns).

Solve the equations.

Check whether your answer makes sense (units, order of magnitude, etc.).Slide7

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Review of some basic concepts

Vectors

Keep track of 2 or more components (or magnitude and direction)

Examples

Position vector

Velocity

Acceleration

Force

Momentum

Scalars

Single (signed) quantity

Examples

Time

Energy

Kinetic energy

Work

Potential energy

Pressure

Temperature

Mass

Density

VolumeSlide8

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Review of some basic concepts

Newton’s second lawSlide9

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Review of some basic concepts

Newton’s second law for angular motionSlide10

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10

Review of energy concepts:Slide11

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11

Summary of work, potential energy, kinetic energy relationshipsSlide12

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12

Extension of concepts of energy conservation to extended objectsSlide13

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13

CM

CMSlide14

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14

Three round balls, each having a mass M and radius R, start from rest at the top of the incline. After they are released, they roll without slipping down the incline. Which ball will reach the bottom first?

A

B

CSlide15

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15

iclicker

exercise:

In previous example which of the equations on your equation sheet would be most useful?Slide16

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From your questions -- (question from Exam 2) Slide17

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Comment on circular motion -- uniform circular motionSlide18

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18

r

In terms of time period

T

for one cycle:

In terms of the frequency

f

of complete cycles:

Comment on circular motion -- uniform circular motionSlide19

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19

Comment on circular motion -- uniform circular motion – effects on gravitationally attractive bodiesSlide20

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20

Comment on circular motion -- non-uniform circular motion

r

At each instant of time

Note that if speed

v

is

not

constant, then there will

also

be a tangential component of acceleration:

a

c

a

qSlide21

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21

From your questions -- (question from Exam 1)

Neglecting any possible

dissipative

forces acting on this system, determine the magnitude of the velocity of the ball

v

f

as it is caught by the person at the coordinates (

x

f

,y

f

).

What

is the angle

q

f

?

Determine

the net work of gravity on the ball at it moves from the initial to final positions in its trajectory: .Slide22

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22

From your questions -- (question from Exam 1)

Neglecting any possible

dissipative

forces acting on this system, determine the magnitude of the velocity of the ball

v

f

as it is caught by the person at the coordinates (

x

f

,y

f

).

What

is the angle

q

f

?

Determine

the net work of gravity on the ball at it moves from the initial to final positions in its trajectory: .Slide23

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From your questions -- force diagrams

m

q

1

q

2

F

1

F

2

mgSlide24

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24

mg(-

j

)

r

T

q

F

=m

a

T- mg

cos

q = 0

-

mg sin

q = -

ma

q

t

=I

a

r mg sin

q

= mr

2

a =

mra

q

From your questions -- pendulumSlide25

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25

From your questions --

driven Harmonic oscillatorSlide26

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26

From your questions --

driven Harmonic oscillatorSlide27

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Similar problem from

webassign

:

Damping is negligible for a 0.165-kg object hanging from a light, 6.30-N/m spring. A sinusoidal force with an amplitude of 1.70 N drives the system. At what frequency will the force make the object vibrate with an amplitude of 0.600m?

(usually neglected)Slide28

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Examples of two-dimensional collision;

balls

moving on a frictionless surfaceSlide29

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Examples of two-dimensional collision;

balls

moving on a frictionless

surface – energy conservation?

Note: In these collision analyses, we are neglecting forces and potential energy

iclicker

question

Why?

We are cheating physics

We are applying the laws of physics correctlySlide30

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Examples of two-dimensional collision;

balls

moving on a frictionless

surface – energy conservation?

Assuming that we applying the laws of physics correctly – we can ask the question – Is (kinetic) energy conserved?Slide31

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31

From your questions -- conservation

of angular momentum

m

m

d

1

d

1

m

m

d

2

d

2

I

1

=2md

1

2

I

2

=2md

2

2

I

1

w

1

=I

2

w

2

w

2

=

w

1

I

1

/I

2

w

1

w

2Slide32

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Example form

Webassign

#11

X

t

1

t

3

t

2

iclicker

exercise

When the pivot point is O, which torque is zero?

A.

t

1

?

B.

t

2

?

C.

t

3

?Slide33

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33

An

example of the application of torque on a rigid object:

A horizontal 800 N merry-go-round is a solid disc of radius 1.50 m and is started from rest by a constant horizontal force of 50 N applied tangentially to the cylinder. Find the kinetic energy of solid cylinder after 3 s.

K = ½ I

w

2

t = I a w =

w

i

+ a

t =

a

t

In this case I = ½ m R

2

and

t

= FR

R

FSlide34

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Webassign

questions on fluids (Assignment #17)

A hypodermic syringe contains a medicine with the density of water (see figure below). The barrel of the syringe has a cross-sectional area 

A

 = 2.40  10

-5

 m

2

, and the needle has a cross-sectional area 

a

 = 1.00  10

-8

 m

2

. In the absence of a force on the plunger, the pressure everywhere is 1.00 atm. A force  of magnitude 2.65 N acts on the plunger, making medicine squirt horizontally from the needle. Determine the speed of the medicine as it leaves the needle's tip. 

 Slide35

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35

Send email or come to see me if you have further questions.

THANKS!