A) 256 J
B) 486 J
C) 524 J
D) 324 J
Correct Answer: B
Solution :
Key Idea: The linear momentum of exploding part will remain conserved. |
Applying conservation of linear momentum, we write, \[{{m}_{1}}{{u}_{1}}={{m}_{2}}{{u}_{2}}\] |
Here, \[{{m}_{1}}=18\,kg,\,{{m}_{2}}=12\,kg\] |
\[{{u}_{1}}=6\,m{{s}^{-1}},\,\,{{u}_{2}}=\,\,?\] |
\[\therefore \] \[18\times 6=12\,{{u}_{2}}\] |
\[\Rightarrow \] \[{{u}_{2}}=\frac{18\times 6}{12}=9\,m{{s}^{-1}}\] |
Thus, kinetic energy of 12 kg mass |
\[{{K}_{2}}=\frac{1}{2}\,{{m}_{2}}u_{2}^{2}\] |
\[=\frac{1}{2}\times 12\times {{(9)}^{2}}\] |
\[=6\times 81\] |
\[=\text{ }486J\] |
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