A) \[8\times {{10}^{-4}}\]
B) \[4\times {{10}^{-4}}\]
C) \[8\times {{10}^{-5}}\]
D) \[4\times {{10}^{-5}}\]
Correct Answer: D
Solution :
Forces acting on the mass are the tension T and the weight W. At the lowest point, \[T-W=\frac{m{{v}^{2}}}{r}\] or \[T=W+mr{{\omega }^{2}}\] \[(\because v=r\omega )\] \[=6.5\times 9.8+6.5\times 0.60\times {{(2)}^{2}}\] \[=63.7+15.6\] \[=79.3\,N\] We have, \[Y=\frac{TL}{Al}\] \[\Rightarrow \] \[l=\frac{TL}{Ay}\] \[=\frac{79.3\times 0.60}{0.05\times {{10}^{-4}}\times 2\times {{10}^{11}}}\] \[=475.8\times {{10}^{-7}}m\] \[4.75\times {{10}^{-5}}\,m\] \[\approx 4\times {{10}^{-5}}\,m\]You need to login to perform this action.
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