中北大学材料科学与工程基础试题及答案(2)

(3) A cylindrical specimen of some alloy 8 mm in diameter is stressed elastically in

tension. A force of 15,700 N produces a reduction in specimen diameter of 5×10 mm. Compute

-3

Poisson’s ratio for this material if its modulus of elasticity is 140 GPa.

(4) Below, molecular weight data for a polypropylene material are tabulated. Compute

(a) the number-average molecular weight, (b) the weight-average molecular weight, (c) the number-average degree of polymerization, and (d) the weight-average degree of polymerization.

Molecular Weight xi wi Range (g/mol ) 5000-10000 10000-15000 15000-20000 20000-25000 25000-30000 3000040000

0.05 0.16 0.24 0.28 0.20 0.07 0.02 0.10 0.20 0.30 0.27 0.11

百度搜索“77cn”或“免费范文网”即可找到本站免费阅读全部范文。收藏本站方便下次阅读，免费范文网，提供经典小说综合文库中北大学材料科学与工程基础试题及答案(2)在线全文阅读。