Experimental determination of Young's modulus of t

px215467

Experimental determination of Young's modulus of the uncertainty

Young's modulus relative uncertainty of the transfer formula: £ E a U a hundred living in general textbooks, used by poor method Ah, uncertainty of estimates of E in order to deal with such precision to analyze. However I believe that despite the nominal value of each weight are the same, but inevitably there are individual differences, leading to changes in weight of the steel produced each time the tension between difference also exists, so strictly speaking, for Ah the calculation should be treated as a problem of unequal precision. 2 uncertainty analysis textbooks in general, on L, D, b only requires another test, their inconvenience A type uncertainty is estimated to B type uncertainty generally expressed its uncertainty, with △ instrument measuring instruments used in that instrument error, a UL a (3) √ 3UD = (4) √ 3Ub a (5) * Received date :2004-06-10. E-mail: lizhuof @ sohu. com About the author: Li Zhuo ~ (1979), female, Guangdong Jieyang people, Director, Research Institute, Research Interests: Physics. 290 Baoji University (Natural Science) 2004, refused to wire diameter d, the A type uncertainty 【, strong, B type uncertainty and the combined uncertainty, respectively: U to a Ua a, / i A , u twist a full-√ 3 (6) the uncertainty weight: AUM one -: Z. AM (7) √ 3 by Unequal weighting Ah: The experiment requires one for every additional 1kg weight scale readings recorded until 8kg, and then read a sequential number for each 1kg less, repeated 3 times (ie, add the same weight reading times). So first find the weight difference when △ △ h 1kg a Σ (Doo (A 6) Jun measurements for each group pi = 1 weighted uncertainty U of a (a 7) (= 7) (8) measured by the D, L, b, d, M (M a 1kg) and Ah substituted into (1), we can obtained Young's modulus E. Then (3) ~ (8) generation (2) Young's modulus can be obtained relative uncertainty. Young's modulus of uncertainty: U £ a E · £ (P A 68.3) 3 3.1 data processing data processing precision measurement ranging from the measured object for the wire, the local acceleration of gravity is 9.788m / s , measured data (Table 1 Table 3) and the results are as follows. Table 1 Changes in weight scale reading when the corresponding unit: cm = 0.3845cm, U = 0.0116cm. Table 2 U wire diameter of a 0.0004cm. 4 Zhuo where other experimental Young modulus determination of the uncertainty to be measured 291,[link widoczny dla zalogowanych], Table 3 and the instrumental error in Table 3 from Table 1 the data can be obtained: E a-8M Korea gLD eleven 1.9408 × 10nN / m2rtdz6 △ h ~ an e ==:× 10uN/m23.2 data processing and other precision measurement will be the same quality of steel when added 6 read data (Table 4) average, calculated. Difference method used by Ah, that is divided into 4 groups, each two readings of the weight of poor quality is 4kg. Lord of the West one (a 4) Table 4 Changes in weight scale reading when the corresponding unit: cm = 1.54cm, = o. o817cm. Data with the rest of Table 2, Table 3. E a-8M per gLD-1.9411 × 10'N / mz7cd. 6 △ h ~ ... e of a √ + + +4 + + a, / ten ten ten 1. Weight difference between the calculation of Ah were weighted, the result of the error is small. Can be seen as the Ah measurement precision measurement ranging from reasonable to process the data. A 5.4%