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DUE 0737458. Multiple Representations of Buoyancy. Jessica Oliveira, Meredith Weglarz, & James Vesenka University of New England jvesenka@une.edu UNH Colleagues Dawn Meredith Jessica Bolker Chris Schubert. Motivation. UNE: Modeling Approach Student centered, guided inquiry labs
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DUE 0737458 Multiple Representations of Buoyancy Jessica Oliveira, Meredith Weglarz, & James Vesenka University of New England jvesenka@une.edu UNH Colleagues Dawn Meredith Jessica Bolker Chris Schubert WDC APS/AAPT
Motivation • UNE: Modeling Approach • Student centered, guided inquiry labs • Lab first, discussion (class) second • DAILY online homework • Service to life science majors • One month of fluids • Buoyancy, important concept for biology • Multiple representation activity? • Continuum representation? • Preconceptions -> assessment WDC APS/AAPT
Clicker ? • A can of soda is “immersed” in air. What direction(s) does the air “push” on the soda can, in total? • Up • Down • Sideways • All of the above WDC APS/AAPT
Clicker ? • The can is immersed in water. What direction(s) do the water molecules “push” on the can, in total? • Up • Down • Sideways • All of the above WDC APS/AAPT
The New Lab Fb +0.041 N -0.039 N FT Fg Fg FT +z WDC APS/AAPT
Experimental Data Fb FT Fg Fb Fb Fg Fg FT Neutral Buoyancy F=Fb+Fg+FT=0 FT=-Fg-Fb FT = Fg - Fb Slope = 1 Intercept = -Fb Fb = gV= 0.062N WDC APS/AAPT
Modeling Cycle Exam Start/stop Pre-lab Definitions Consensus Operational Definitions Multiple Representations Graph, Math Diagram, Verbal Deployment Refine Operations Decisions Test-Works? Paradigm Lab No Yes WDC APS/AAPT
The Spherical Fish WDC APS/AAPT
Post/Pre Test Analysis Switched to symbolic math model WDC APS/AAPT
Force of water? Fwu Fwu Fwu Fwu Fb Fg Fwa Fwa Fg Fwa Fg • Molecular picture ("u"=under, "a"=above). WDC APS/AAPT
Clicker ? 1 3 2 1 60 • Which way will the Helium balloon move when the box is first moved to the right? Why? • Right • Left • No motion • Clueless WDC APS/AAPT
Volume of the fish Fb Fg • At neutral buoyancy Fg = Fb mg = mwg = wgV' V'=V-Vwin Vwin = 0.16mL -> 3.4 mL WDC APS/AAPT
Bonus: Hydrostatic P • Lab just completed is hydrostatic pressure: P = Pref +gz P = gz • Estimate depth at pressure in bottle z = P/g ≈ 2m WDC APS/AAPT
Clicker ? • What is the smallest amount of water needed to float an ocean liner? • An ocean • A lake • A bathtub full • A teaspoonful How big is this force? WDC APS/AAPT
Archimede’s Principle • Archimede: 287-212 BC • Fb = weight of displaced water = mwg • How do we determine mass of water without a scale? • mw=rwV -> Fb=rwgV • SF = Fb+FT-Fg=0 • Fb = Fg - FT water mass mass WDC APS/AAPT
Clicker ? • A hole is drilled in a piece of wood, will it float higher, lower or the same after the hole has been drilled? • Higher • Lower • No difference • Clueless WDC APS/AAPT
Clicker ? • Merchant ships routinely dumped their ballast overboard before taking on cargo. In an enclosed lock, the water… • Rises • Lowers • No difference • Clueless WDC APS/AAPT
Clicker ? • 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? WDC APS/AAPT