© 2009 WGBH Educational Foundation. CHALLENGE JET fl Brainstorm • • • thechallenge Introduce Brainstorm Newton’s 3 Preparation Challenge: The ies straight and far under its own power. its under far and straight ies Gatherthesematerials (perteamoftwo).Seepage44forsuppliers. pbs.org/designsquadanddownloadthefollowingvideoclipsfrom Visit • • What forcedoesthejet’s overcome? thrust without having to thejetfromblimp.) detach apumpuse to infl ate theballoon. such how connecting Mylar astheframe place, Demonstrate thetwo . to easy-to-access stable, a to it attach should they point, to it want students where thejetto theblimp.(Attach To that pointing assure theendofjetstays exactly How canyouusethisjettoprovide fromtheballoon.) help airthe straw how can control escapes fast balloonandastraw andmake ajet.(Seeillustration.) latex party case, balloon)sotheirblimpsfl aparty y undertheirownjetpower. Holdup a Tell studentsthattoday’s challengeistoaddajetpropulsion system(inthis Laws “Teacher’s Guide”page: NOTE: and be able to work precisely. precisely. work to able be and patient be must students path, astraight to to ablimp travel get oftesting many rounds • • • to work carefully and precisely.) onhow theblimp why This travels. is effect noticeable students willing must be blimp to small travel. ofwhere adjustments Very have thestraw points a Which way shouldthestraw point? theblimp also forward.) pushes unbalanced force to theblimp, thehole. theballoonthe area attached Since opposite is this thehole. theballoonopposite So, moves in thedirection ofthegreater force— balloon are now unbalanced—there agreater is pushing force onthearea than it on pressure less hole—has area with the oneareahole. oftheinside surface—the Whenthis happens, balloon. outofthe Butwhen oftheballoon, theair theneck you open rushes ofthe onall equal outequally sothereis force air parts onall pushes sides, How isthisjetanexampleofNewton’s 3rdLaw clear tape 4 sheetsofpaper previous challenge from

(1 minute).Bepreparedtoprojectthem. In Blimp Jet, there are many more variables than in Sky . Because it can take take can it Glider. inSky Because than many variables are more there Jet, In Blimp (10 minutes)

Add a jet-propulsion system (i.e., ablimp ajet-propulsion sothat Add a balloon) (5 minutes) rd Law Newton’s 3 • • • (narrow andwide) (narrow 6 drinkingstraws scissors balloon pump

Point outhow you thestraw infl lets ate the thrust rd the other parts. The forces inside the Theforces the otherparts. (Opposite thedirection students want(Opposite the Law —a pushingforce—toablimp?

(1 minute)and (Inertia and air resistance [i.e., and drag]) air resistance (Inertia ? (Inside asealed balloon, the ? (Inside • down awkwardly.) buthang also work “” balloons balloon(Long party 12- to16-inchlatex Thrust & Newton’s &Newton’s Thrust (Mention that (Mention with tape. with balloon’s ittightly Seal neck. “jet.” into astraw Fit the a make blimp, a To propel jet Make ablimp the blimp’s fl ight. doesn’t signifi cantly impair blimp lookungainly, butit An infl ated jetmakes a

39 40 of achievement. far—gives kidsarealsense to travel straight and challenge—getting ablimp Accomplishing the resistance. streamlined blimp, duetoair travel asfaramore designwon’t This particular to helpablimpfl y straight. Students attachpaperfi ns Here aresomestrategiesfordealingwithissuesthatmay comeupduringbuilding: redesign and test, Build, • • Brainstorm the design process thedesign Brainstorm Summarize the problem tosolve theproblem Summarize • • • • • • • • pair up and brainstorm theirownwayspair upandbrainstorm toaddajet. To promotecreativethinkingandfosterasenseofownership, have students fltest theblimp etc.) ight and to how jet; understand to modify inflmount thejet; makeate document minor each theballoon; easily; adjustments things you’ll needtofi gure outasyouaddajettoyourblimp? Break thelargerchallengeintoitssub-challenges.Ask:Whataresomeof and have afun, memorableexperiencewithNewton’s 3 A second class period? period? class A second More airisnotalways theanswer! straw stillfi ts intothepump.Overfi lling balloonswill, ofcourse, popthem. to adjusttherateofescapingair. Justmake surethattheendoftheir andairresistance.Studentsmightneedtomodifythestraw overcome inertia out.Iftheair escapestooslowly,rapidly peters there’s to toolittlethrust difference. Ifairescapestooquickly, ispowerful, theinitialthrust butit Control thejetpower: Control places. place. To anchoritwell, students shouldtapeittotheframeinatleasttwo Tape thejetfi tape theballoonjettoward thebottomofblimp. Orient theblimp: buoyant again. balloon jet, studentswillneedtoadjusttheirblimpsmake themneutrally Make blimps neutrally buoyant: buoyant: neutrally Make blimps the thinstraw canslipintoaballoonjet’s straw. fi athinstrawt intostraws.thepumptipandsealitwithtape.Now Insert Modify the balloon pump: theballoon Modify Newton’s 3 principle. Also point out the importance ofreducingweight. principle. Alsopointouttheimportance usingan action-reaction provides thrust Discuss howtheirblimpjetsimilarly build afl ying footballgoalpost andgrapplewithbalancinggravity andthrust. two sessionsto make sure theair stream fl andows freely not is by blocked blimp parts.) Brainstorm goodplacestoattachthejet. Brainstorm Watch both rd Newton’s Laws Law topropelandsteerafan-propelledboat.Intheother, they rmly inplace: Blimp Jet Top-heavy blimpsdon’t stay level. Encouragestudentsto (30minutes) Theamountofairleaving theballoonjetmakes a Students canachieve successinoneclassperiod willreallyletstudentsrefi ne theirsystems. Tipsoncommercialballoonpumpsaretoobigto

videos. Inone, the Theballoonjetwigglesifkidstapeitinonlyone (5 minutes) To compensatefortheaddedweight ofthe (A bottom-heavy blimp is more stable; stable; more is blimp bottom-heavy (A Design Squad Squad Design rd Law. Butdevoting (Decide how to: how to: (Decide teams use

© 2009 WGBH Educational Foundation.