(2)AG=∫dG=∫adA=o△4 姓：小2》语 =twnl88g-1s10 △G=(0.07275Jm2)(1.26×10-2m2) =9.17×104灯 W,=△G=9.130×104灯(2) = S S ∆G = dG dA = ∆A ∫ ∫σ σ ( ) ⎟⎟⎠⎞ ⎜⎜⎝⎛ = − ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∆ = − = − 4 1 3 3 34 2 2 1 1 2 1 3 S ,2 ,1 1 rr r r r A V A A r V V π π ( ) 2 2 63 2 3 1 1.26 10 1.00 10 1.00 10 4 1.00 10 m mm m − −− − = × ⎟⎟⎠⎞ ⎜⎜⎝⎛ − ×× = π × ∆G＝(0.072 75 J·m-2)(1.26×10-2 m2) ＝9.17×10-4J Wr＝∆G＝9.130×10-4J