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1、Measure the moment of inertia of anobject with three wire pendulumEnglishName:maxChineseName:wanghaotianStudentNumber:1417454061Major: Electrical engineering and its automation(Sinoforeign cooperative education)1.INTRODUCTION1) Aims of the experiment:1. Toresearch the rotary inertia ,mass and form(u
2、niform destiny)of one object ,and the relation between Rotor position and the object.2. study the method of measuring rotary inertia in three wire twist method.2) Brief contents of experiment:1. When the three wire twist after leveling, twist on the plate( a5degree), Torsional pendulum movement in t
3、he three wire pendulum, by the theory of the rotational inertia of the driven disc forI0the mo of the type,For the quality of the hanging plate,g is the acceleration of gravity ,R and r respectively are on the footwall and the three plate of three wire pendulum suspension points center of gravity to
4、 the hanging point distance .H is the vertical distance between the two discs .T0 is the hanging plate twist cycle.2. If the quality of m objects symmetrically on the disc m0 under test，IsoT of the type is their Swing cycle. suppose k=gRr/4pai1.record the mass m0 of disc ,and the mass of A,B,mA,mB.2
5、.1)measure the inside and externaldiameter of discD0insideand D0externalby vernier caliper. measure the diameter of cylindricalDA by vernier caliper. measure the inside and externaldiameter of annulus DBinsideand DBexternaL by vernier caliper.H,so I0=km0T02,I=k(mo+m)T2Iobject=I-I0=km0(T2-T02)+mT22.E
6、XPERIMENTAL1) Apparatus:Three wire twist, the cylinder sample (two), ring sample B, level, A stopwatch (0.01 s), metric scale (1 mm), vernier caliper (0.02 mm) .2) Procedure:4) measure and calculate the distance between the up-circle ,down-circle and center of a circle,r and R.3. adjust the column s
7、traight, With level leveling footwall, first make level parallel with two adjusting screw connection, then with both hands at the same time operating the two suspension line length adjusting with the adjust screw, adjust the level after he turned 90 degrees ,and level another adjusting screw, do it
8、two times and you can level it, measure H by meter ruler.4. Twist on disc( a5degree), do torsional pendulum motion by suspension line under the torsion of the disc,5. after waiting for disk do stability under swing, Press the stopwatch and starting from 0 for oscillation frequency, get the total tim
9、e to write down the full swing 50 times, and calculate its cycle. do the experiment 3 times, calculate the T06. put example A on the lower circle, align its center and the discs center, repeat step 4 and 5 ,then calculate the T17. put two same example A, in symmetry position of circles center, and m
10、ake its edge tangent circles center , repeat step 4 and 5,then calculate the T18. put example B on the lower circle, align its center and the discs center, repeat step 4 and 5 ,then calculate the T13. RESULTSDatum from measurements:Table 1t/sT(30 times)uc,T12345lower disc20.9619.8420.0620.1720.2920.
11、2691.390.0047lower disc and ring20.0919.7620.1919.7019.9719.9421.370.0047Table 2lower disc mring Mmass/gm=1129M=403diameter/cmD=19.0D outside14.9Djnside10.0distance between two points of upper disca17.7a +a +ar= 1 p 3-4.43 3寸3a27.7a37.65distance between two points of lower discb116.1R=b+=9.333*316.2
12、16.2H/cm43.1Table 3Lower circle(m)Lower circle(m) + ringringexperimentalI(kg*m2)0.00510.00680.0012valueUc1(kg*m2)1.13x10-51.30x10-51.21x10-5l=l+-Uc , 1I(kg*m2)0.004790.006790.00119theoretical valueI(kg*m2)0.00500.00700.0027error (percentage)4%2.8%2.9%inertia of the disc and samples of A and B of the
13、 experimental value and and theoretical value,_ I I -(L理/实xlOO%)Calculate the percentage error 理Moment of inertia of the circle to the theoretical value is显 m( D )2220 Moment of inertia of Annulus for the theoretical value isD(外)2 + (2D内)224.DISCUSSION AND CONCLUSION1.When we use vernier caliper, we need to read the value correctly. After measurement, we need to release a distance between measuring rod and measuring anvil.2. We should use the level correctly to make lower disc horizontal.3. When measure the time, we should use the counting machine correctly.
