reure and Denity uid reure rchiede rincipe Buoyant orce aca rincipe Tabe 4-4, p. 145 reure in uid uid: a atter which can fow (gae or iquid). uid reure Conider a coun of a fuid. What i the preure at the botto of the coun? Lab 5. reure & denity. reure i the ae on every direction in a fuid at a given depth. Exape of fuid: air,, acoho, ercury. 1. uid ay have different denity.. uid exert preure in a direction.. The force due to fuid preure away act perpendicuar to any urface it i in contact with. weight G g 1. The weight of a fuid: DV G DVg D(abh)g Dhg ab V abh weight G DVg - a, D - denity, V - voue, g - acceeration due to gravity. The preure created by a fuid at the botto of the coun: gauge D hg - preure, D - denity, h - height, g - acceeration due to gravity a b Gauge h Note that the fuid i not in otion! gauge i o-caed gauge preure. How we can cacuate preure producing by any fuid? Gauge preure depend on denity of fuid and depth! 4 ig. 4-6, p. 149 Tabe 4-, p. 19
Meaureent of topheric reure: Mercury Baroeter The ga tube i copetey fied with ercury and then inverted into the bow of ercury. coun of ercury 76 c 760 exert the ae preure a the atophere: D g h kg Denity of Hg : D 1600 Why ue uch a dene iquid? h D g h 10. 4 1 at ir preure 5 Dg h (1.6! 10 kg / )(9.8 / )(0.76 ) 1.01! 10 N / 1 at 7 topheric reure topheric preure i defined a: 1 at 76 c Hg 1.01 10 5 a How high woud rie in a coed inverted coun, at 1 at? The preure at the bae of the coun,!gh, i 1 at: 1.01 10 5 a (10 kg/)(9.8/)(h); thu h10. 8 baoon that wa partiay infated near the ea eve expanded a the experienter cibed the ountain. ig. 4-7, p. 150 9 Gauge reure We have a narrow pipe with of 0 height and tower with 0 of height (ee beow). reure gauge paced at the botto how: 1) Larger preure for the tower ) The ae preure ) Larger preure for the pipe with 4) Depend on the radiu of the pipe Gauge preure: gauge!hg pipe 0 tower ig. 4-8, p. 151 reure gauge 11
rchiede rincipe and Buoyancy rchiide principe and Buoyant force. Soe object paced in fuid can foat on the urface or at oe depth. (B!Vg, Buoyant forceweight of fuid dipaced) The reaon: buoyant force B act on the. ig. 9.15 Static equiibriu: B weight G O g 1 B(-1)!fg(h-h1)!fgV!f i the denity of the fuid The preure acting on a botto of the upended eta bock i greater than that on the top due to increae of preure with depth 1 1. The buoyant force on the object foating in a fuid i equa to the weight of the object.. The buoyant force on the object iered in a fuid i equa to the weight of the uberged fuid. 1 Buoyant force Weight of Buoyant orce! bouyant bouyant B!B! <! B <!C C bouyant!c Water bouyant object g (!objectvobject )g bouyant Wdipaced dipaced bouyant < g (!Vdipaced )g (!Vuberged object )g 14 ig. 4-5, p. 155 BUOYNT ORCE, RCHIMEDES RINCILE ig. 4-, p. 15
Buoyant orce Wi an ice cube foat higher in or in acoho? robe 1: Denity of i approx 1g/ Denity of ice i approx 0.9g/ Denity of 100% pure ethano i 0.79g/ Weight of ice W g!vg 1.5-kg bock of wood i foating in. What i the agnitude of the buoyant force acting on the bock? B weight of the object O g ( 1.5 kg)( 9.8 robe : W (0.9g / c )(1c )10 / ) 9.N foating boat dipace of (Dw 1000 kg/). Bouyant!uidVg Water : 1. What i the a of the dipaced by the boat? Bouyant!uidVg (1g / c )(1c )(10 / ) 10N Bouyant > W Dw Ice cube foat in coho : Bouyant!uidVg (0.79g / c )(1c )(10 / ) 7.9N ) 14.7 N w Vw w DwVw ( 1000 kg )( ) 000 kg. What i the buoyant force acting on the boat? B weight of the dipaced w g ( 000 kg)( 9.8 Bouyant < W. What i the weight of the boat? Thu ice cube woud not foat at a in 100% pure ethano. ) 9 400 N weight 9 400 N 15 ig. 4-40, p. 160 ig. 4-8a, p. 158 Zeppein Hindenburg: Buoyant orce in ir aca rincipe Launched in 196, crahed in 197 in Lakehurt, NJ The zeppein LZ-19 Hindenburg wa one of the arget aircraft ever buit: 45 ong, 41 in diaeter, 11 890 of ga. Deigned to ue heiu, forced to ue hydrogen due to US iitary ebargo. reure in fuid: (preure force ) area In a fuid, the appied force create a preure that i tranitted everywhere throughout the fuid. aca principe: preure appied to an encoed fuid i tranitted undiinihed to a part of the fuid and to the wa of the container. LZ-19 force Boeing 747 piton fuid The buoyant force occur due to difference in denity of air and heiu or hydrogen ir :! air 1. kg/ Heiu :! He 0.18 kg/ Hydrogen :! H 0.089 kg/ cyinder aca principe i widey appied in hydrauic yte. Can carry : ( " air! " H )Vg [(1.! 0.089) kg/ ](11 890 )(9.8 / ) 07 015 N 16 17
Ue aca rincipe in Hydrauic Syte Hydrauic yte conit of two or ore piton: Sa piton Large piton! r! r in out in out 18