大学物理实验报告英文版--液体粘滞系数测量.doc

Physical Lab Report : Measurement of Liquid Viscosity Writer: No. Experiment 1: using falling ball method Experiment 2: using comparative method Goal of the experiment 1.Get familiar with basic tools to measure length,time,weight,etc. 2.Through the measurement of viscosity,learn principles about uncertainty evaluation. Principle of the experiment Experiment 1 G.G.Stokes derived the frictional force as .When the ball move with a constant speed v,the frictional force ,the buoyant force,and gravity reach the equilibrium,so we have: (1)Therefore ,the viscosity can be measured by measuring the constant velocity via: (2)However,we estimate the complicated one to be simper: , (3)Where is the density of the liquid and is the density of the ball.Since ,so the final formula is : (4)Experiment 2 Use comparative method,where is the density of water, is the density of the liquid, is the time required for water surface to drop from A to B, is the time for the liquid. Measurements Experiment 1According to the formula,we have to measure the distance between two laser beams s, the time t, the diameter of the ball d , the diameter of the cylinder D, the density of the liquid and the mass of a ball m. Experiment 2 Keep the volume constant, we need to measure the density of water,ethanol,and glucose;the time they need for the surface drop from A to B. Experimental data and analysisExperiment 1A.measurement of sAt first, I adjusted the base plate , and marked the laser spots on the wire.then I measured the distance between two spots on the wire with a ruler 10 times. i12345678910si /cm20.6120.6320.6520.6320.6720.6220.6920.6820.7020.67 Then,I use MATLAB to get the B.measurement of DSecondly,I used the caliper to measure the inner diameter of the cylinder for 10 times.i12345678910Di /mm58.1058.0458.0058.2858.1058.1258.1258.1258.1458.02Then,I use MATLAB to get the .C.measurement of tThirdly,I placed a ball into the guide .When the ball crosses the upper laser light,I start the stop watch;when it crosses the lower laser light,I stop the stop watch.i12345678910t/s11.8211.8411.9211.9011.7811.6811.6911.8111.9311.68Then,I use MATLAB to get the .D.measurement of dFourthly,I used the micrometer to measure the diameter of the steel balli12345678910di/mm2.0072.0072.0082.0062.0072.0082.0082.0062.0082.007Then,I use MATLAB to get the .E.measurement of mass of the ballI make a linear fit of mass vs N to get the mass of a ballThe experimental data is :N1020304050m/g0.3300.6580.9891.3391.638And I made a fit linear:From the graph and MTLAB,I get .F.measurement of I use the liquid density meter to read the density of the sesame oil.G.Environmental record T=21.5Experiment 2 (T=15)ItemLiquidDistilled waterEthanolGlucoseFluid volume ( ml )10.010.010.0Characteristic time for the fluid surface to drop from A to B ( s )171.2114.8145.8271.2114.6146.4371.4116.0145.0470.8116.2144.6570.8116.8144.8670.8116.0143.6averageDensity ( kg/m3 )=0.7950.001Viscosity ( Pas) Conclusion and error analysisExperiment 1According to (4),we have :Put the results above into (5),I got the result: Hence,we have: I use MATLAB to get:besides,we already have Put them into (6),immediately,I got the error:Hence, T=21.5Experiment 2 , , ( s ) with MATLAB,I know: Hence, T=15.0Similarly,we have the result T=15.0 Discussion and error analysisExperiment 11.In the equation,we omit the corrections of the order of r/h,which makes our result a littler lager than the exact one.2.The principle of the Liquid density meter:It is based on the condition that the buoyant force is equal to the gravity.Where.Different liquid has different density,so the meter has different height h.So,in different liquid,the height overwhelmed in liquid is different,resulting that we can read different density,3.Errors:Maybe there are some bubbles in the liquid,which will make the final result lager.Though I have make efforts to let the ball fall from the center,the steel ball still may not fall along the direct line from the center.The temperature is changing during my experiment,which has a great influence on the final result.Although I have read the temperature twice,there must be errors.Experiment 21. The volume of the liquid input to the viscometer has to be a constant because we use the comparative method. In this method,we only use the equation, which has omit the volume V, so we have to keep the volume a constant,otherwise, this equation is meaningless.2.Errors:There are several small bubbles in the liquid,which has an influence on the final result.Its subjective t