February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT 11

Multiple Representations

of Buoyancy

Multiple Representations

of BuoyancyJessica Oliveira, Meredith Weglarz, & James VesenkaUniversity of New England

jvesenka@une.edu

UNH ColleaguesDawn MeredithJessica BolkerChris Schubert

Jessica Oliveira, Meredith Weglarz, & James VesenkaUniversity of New England

jvesenka@une.edu

UNH ColleaguesDawn MeredithJessica BolkerChris Schubert

DUE 0737458

February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT Page 2Page 2

MotivationMotivation UNE: Modeling Approach

Student centered, guided inquiry labsLab first, discussion (class) secondDAILY online homework

Service to life science majorsOne month of fluidsBuoyancy, important concept for biology

Multiple representation activity?Continuum representation?Preconceptions -> assessment

UNE: Modeling ApproachStudent centered, guided inquiry labsLab first, discussion (class) secondDAILY online homework

Service to life science majorsOne month of fluidsBuoyancy, important concept for biology

Multiple representation activity?Continuum representation?Preconceptions -> assessment

February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT Page 3Page 3

Clicker ?Clicker ?

1 2 3 4

0% 30%20%50%

1. Up2. Down3. Sideways4. All of the above

1. Up2. Down3. Sideways4. All of the above

A can of soda is “immersed” in air. What direction(s) does the air “push” on the soda can, in total?

February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT Page 4Page 4

Clicker ?Clicker ?

1 2 3 4

75% 15%10%0%

1. Up2. Down3. Sideways4. All of the above

1. Up2. Down3. Sideways4. All of the above

The can is immersed in water. What direction(s) do the water molecules “push” on the can, in total?

February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT Page 5Page 5

Fg

The New LabThe New Lab

+z

+0.041 NFT

Fg

-0.039 N

FT

Fb

February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT Page 6Page 6

Experimental DataExperimental Data

Fg FT

Fb

Fg

FT Fb

F=Fb+Fg+FT=0FT=-Fg-Fb

FT = Fg - Fb

Slope = 1Intercept = -Fb

Fb = gV= 0.062N

Fg

Fb

Neutral Buoyancy

February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT Page 7Page 7

Modeling CycleModeling CycleStart/stop

Definitions

Operations

Decisions

Yes

ConsensusParadigm Lab

Pre-lab

Operational

Definitions

Multiple Representatio

ns

Graph, Math

Diagram, Verbal

Test-Works?No

Refine

Deployment

Exam

February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT Page 8Page 8

The Spherical FishThe Spherical Fish

QuickTime™ and aMPEG-4 Video decompressor

are needed to see this picture.

Vf ish

=m

w

−Vair

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Spring 2009 Buoyancy

0

10

20

30

40

50

60

70

80

90

Graphical Mathematical Verbal Diagrammatic

Representation

Percent Correct

Pre

Post

Post/Pre Test AnalysisPost/Pre Test Analysis

Switched to symbolic math model

February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT Page 10Page 10

QuickTime™ and aH.264 decompressor

are needed to see this picture.

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Force of water?Force of water? Molecular picture ("u"=under, "a"=above).

Molecular picture ("u"=under, "a"=above).

Fg

FwuFwu

Fwa

Fg

Fwu

Fwa

Fg

Fwu

Fwa

Fb

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Clicker ?Clicker ?

1 2 3 4

70% 0%10%20%

1. Right2. Left3. No motion4. Clueless

1. Right2. Left3. No motion4. Clueless

Which way will the Helium balloon move when the box is first moved to the right? Why?

123

1

February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT Page 13Page 13

Volume of the fishVolume of the fish

At neutral buoyancy Fg = Fb

mg = mwg = wgV'

V'=V-Vwin

At neutral buoyancy Fg = Fb

mg = mwg = wgV'

V'=V-Vwin

€

V =m

w

−Vwin Fg

Fb

Vwin = 0.16mL -> 3.4 mL

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Bonus: Hydrostatic P Bonus: Hydrostatic P

Lab just completed is hydrostatic pressure:

P = Pref +gz

P = gz Estimate depth at pressure in bottle

z = P/g ≈ 2m

Lab just completed is hydrostatic pressure:

P = Pref +gz

P = gz Estimate depth at pressure in bottle

z = P/g ≈ 2m

QuickTime™ and a decompressor

are needed to see this picture.

QuickTime™ and aMPEG-4 Video decompressor

are needed to see this picture.

February 2010 February 2010 WDC APS/AAPT WDC APS/AAPT Page 15Page 15

Clicker ?Clicker ?

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1. An ocean2. A lake3. A bathtub full4. A teaspoonful

1. An ocean2. A lake3. A bathtub full4. A teaspoonful

What is the smallest amount of water needed to float an ocean liner?

How big is this force?

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Archimede’s PrincipleArchimede’s Principle Archimede: 287-212 BC Fb = weight of displaced water = mwg

How do we determine mass of water without a scale?

mw=wV -> Fb=wgV F = Fb+FT-Fg=0

Fb = Fg - FT

Archimede: 287-212 BC Fb = weight of displaced water = mwg

How do we determine mass of water without a scale?

mw=wV -> Fb=wgV F = Fb+FT-Fg=0

Fb = Fg - FTmass mass

water

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Clicker ?Clicker ?

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25% 25%25%25%

1. Higher2. Lower3. No difference4. Clueless

1. Higher2. Lower3. No difference4. Clueless

A hole is drilled in a piece of wood, will it float higher, lower or the same after the hole has been drilled?

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1. Rises2. Lowers3. No difference4. Clueless

1. Rises2. Lowers3. No difference4. Clueless

Merchant ships routinely dumped their ballast overboard before taking on cargo. In an enclosed lock, the water…

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Clicker ?Clicker ?

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1.

2.

3.

4.

1.

2.

3.

4.

Which way will they go? Two burning candles are suddenly spun in a circle (inside closed containers). The direction the FLAMES will point is…

Why?