Viscosity vs Density
Viscosity thiab ntom yog ob yam khoom ntawm cov kua thiab roj (los yog hu ua kua). Lawv muaj txiaj ntsig zoo rau lub cev thaum nws los piav txog statics thiab dynamics ntawm cov tshuaj no. Viscosity thiab ntom ib leeg tuaj yeem piav qhia ntau tshaj li ib nrab ntawm cov kua dej.
Viscosity
Viscosity txhais tau tias yog qhov ntsuas ntawm qhov tsis kam ntawm cov kua dej uas tau deformed los ntawm kev ntxhov siab los yog kev ntxhov siab tensile. Hauv ntau lo lus, viscosity yog "kev sib txhuam sab hauv" ntawm cov kua dej. Nws tseem hu ua lub thickness ntawm cov kua. Viscosity tsuas yog kev sib txhuam ntawm ob txheej ntawm cov kua dej thaum ob txheej txav mus rau ib leeg. Sir Isaac Newton yog ib tug pioneer hauv dej mechanics. Nws postulated tias, rau ib tug Newtonian kua, lub shear kev nyuaj siab ntawm cov khaubncaws sab nraud povtseg yog proportional rau lub ceev gradient nyob rau hauv cov kev taw qhia perpendicular mus rau lub txheej. Qhov proportional tas li (proportionality factor) siv ntawm no yog viscosity ntawm cov kua. Lub viscosity feem ntau txhais los ntawm Greek tsab ntawv "µ". Viscosity ntawm cov kua tuaj yeem ntsuas tau siv Viscometers thiab Rheometers. Cov units ntawm viscosity yog Pascal-thib ob (los yog Nm-2s). Lub cgs system siv chav tsev "poise", npe tom qab Jean Louis Marie Poiseuille, los ntsuas viscosity. Viscosity ntawm cov kua kuj tuaj yeem ntsuas los ntawm ntau qhov kev sim. Lub viscosity ntawm cov kua yog nyob ntawm qhov kub thiab txias. Lub viscosity txo qis raws li qhov kub thiab txias.
Viscosity sib npaug thiab cov qauv yog qhov nyuaj heev rau cov kua dej uas tsis yog-Newtonian.
Density
Density txhais tau tias yog huab hwm coj ib chav tsev ntim. Qhov ntom ntom ua lub luag haujlwm tseem ceeb hauv cov tshuab ua kua dej. Cov xwm txheej xws li nce thrust yog nyob ntawm qhov ceev. Qhov ntom yog qhov peb ib txwm hu ua "qhov hnyav" ntawm cov kua dej. Qhov ntom ntom yog ib lub tswv yim uas peb paub tiag tiag. Nws tuaj yeem tau txais los ntawm qhov sib npaug yooj yim ceev=ntau / ntim. Nws units yog Kgm-3
Qhov txawv ntawm Viscosity thiab ntom yog dab tsi?
Txawm hais tias feem coob ntawm cov neeg xav tias viscosity thiab ntom yog ob qho tib si uas tau hais los ntawm ntau hom, lawv yog ob lub ntsiab lus sib txawv. Qhov ceev yog qhov ntsuas ntawm qhov hnyav molecular ntawm qhov muaj pes tsawg leeg. Hauv cov lus yooj yim, qhov ceev=tus naj npawb ntawm molecules x molecular hnyav / ntim nyob, thaum lub viscosity yog ib qho kev ntsuas ntawm inter-molecular rog thiab molecule duab. Viscosity qhia koj txog "kev sib txhuam" ntawm ob txheej ntawm cov kua dej, thaum qhov ceev sib txawv me ntsis nrog qhov kub thiab txias, viscosity hloov sai. Ob qhov ceev thiab viscosity txo qis nrog qhov kub thiab txias, tab sis viscosity feem ntau muaj kev sib raug zoo nrog qhov kub thiab txias. Kev ceev tuav ib txoj kev sib raug zoo. Qhov kub viscosity kev sib raug zoo no yog lub hauv paus ntawm nws pib lubricant technology.
Viscosity thiab ntom yog ob qhov sib txawv ntawm lub cev nyob ntawm qhov sib txawv kiag li. Qhov kev xav tsis zoo ntawm "cov kua hnyav dua yog cov viscos ntau dua" yuav tsum tau muab tshem tawm.
