3. 重量計算：(註：鐵之比重量為 $7.87 \mathrm{~g} / \mathrm{cm}^{3}$ )

鐵鏽件之重量為：___1____kg

計算過程：

VA= π(6.5x6.5)(C) ﹣π(4.5x4.5)(A) ﹣〔π(6.5x6.5)(A) ﹣π(4.5x4.5)(A)〕﹣4〔π(1.0x1.0)(B)〕
= 240.22 ㎝³
VB= π(6.5x6.5)(12) ﹣π(5.5x5.5)(10) ﹣π(5.5x5.5)(A)=547.17 ㎝³
V= VA+VB=240.22+547.17
= 787.39 ㎝³
W= 787.39(7.87)
= 6196.8 g
=____2___ kg

1.