A) 3.696 kg
B) 3.6 kg
C) 36 kg
D) 36.9 kg
Correct Answer: A
Solution :
The pipe can be assumed as hollow cylinder. |
External radius \[=\frac{8}{2}=4\,\,\text{cm}\]Thickness \[=1\,\,\text{cm}\] |
\[\therefore \] Internal radius \[=4-1=3\] |
Volume of the material \[=\pi h\,\,({{R}^{2}}-{{r}^{2}})\] |
\[=\frac{22}{7}\times 21\times \,\,({{4}^{2}}-{{3}^{2}})=\frac{22}{7}\times 21\times 7=462\,\,\text{c}{{\text{m}}^{\text{3}}}\] |
Now, \[1\,\,\text{c}{{\text{m}}^{\text{3}}}\]iron weighs \[=8\,\,\text{g}\] |
\[\therefore \]\[462\,\,\text{c}{{\text{m}}^{\text{3}}}\]iron weighs \[=462\times 8\,\,\text{g}=\frac{462\times 8}{1000}\,\,\text{kg}\] |
\[=3.696\,\,\text{kg}\] |
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