大学物理实验报告英文版--液体粘滞系数测量

Physical Lab Report : Measurement of Liquid Viscosity

Writer: No.

Experiment 1: using falling ball method Experiment 2: using comparative method

ⅠGoal 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.

Ⅱ Principle of the experiment Experiment 1

G.G.Stokes derived the frictional force as vr F πη6=.

When the ball move with a constant speed v,the frictional force ,the buoyant force,and gravity reach the equilibrium,so we have:

...)1080

19

1631)(3.31)(4.21(6)(34203+-+++=-e e R R h r R r rv g r πηρρπ

(1) Therefore ,the viscosity can be measured by measuring the constant velocity via:

...)

R R )(h r .)(R r .(s t g )ρ(ρr ηe e +-+++⋅⋅⋅-⋅

⋅=

2

1221080

19163133142192 (2) However,we estimate the complicated one to be simper: D

d

.s

t g )ρ(ρd η4

21118

1'122+⋅

⋅⋅-⋅⋅=, (3)

Where 1ρ is the density of the liquid and 2ρ is the density of the ball.

Since 333426d m

r

m ππρ==,so the final formula is :

D

d .s t

g )ρd m

(

d η4211618

1

13

2+⋅

⋅⋅-⋅⋅=

π (4)

Experiment 2

Use comparative method,1

12212t t ρρηη=,where 1ρ is the density of water, 2ρ is the density of the liquid,

1t is the time required for water surface to drop from A to B, 2t is the time for the liquid.

Ⅲ 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

1ρ 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.

Ⅳ Experimental data and analysis Experiment 1

A.measurement of s

At 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.

i 1 2 3 4 5 6 7 8 9 10

s i /cm 20.61

20.63

20.65

20.63

20.67

20.62

20.69

20.68

20.70

20.67

Then,I use MATLAB to get the cm 01.001.066.20syst stat s ±±=

B.measurement of D

Secondly,I used the caliper to measure the inner diameter of the cylinder for 10 times.

i

1 2 3 4 5 6 7 8 9 10 D i /mm

58.10

58.04

58.00

58.28

58.10

58.12

58.12

58.12

58.14

58.02

Then,I use MATLAB to get the mm 02.002.010.58syst stat D ±±=.

C.measurement of t

Thirdly,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.

i 1 2 3 4 5 6 7 8 9 10

t/s 11.82 11.84 11.92 11.90 11.78 11.68 11.69 11.81 11.93 11.68 Then,I use MATLAB to get the s 01.003.081.11syst stat t ±±=.

D.measurement of d

Fourthly,I used the micrometer to measure the diameter of the steel ball i 1 2 3 4 5 6 7 8

9 10 d i /mm 2.007 2.007 2.008 2.006 2.007 2.008 2.008 2.006 2.008 2.007

Then,I use MATLAB to get the mm 01.001.0007.2±±=d .