A) 11
B) 14
C) 16
D) 15
Correct Answer: C
Solution :
According to questions,\[{{\left( \frac{29}{30}v \right)}^{2}}-{{v}^{2}}=2ax\] ?(i) Let the number of wooden plank is n and hence the thickness of it will be nx, then, \[0-{{v}^{2}}=2anx\] \[\Rightarrow \] \[n=\frac{-{{v}^{2}}}{2ax}\] \[n=\frac{-{{v}^{2}}}{\left( \frac{29}{30} \right){{v}^{2}}-{{v}^{2}}}=\frac{-{{(30)}^{2}}}{{{(29)}^{2}}-{{(30)}^{2}}}\] [from Eq. (i)] \[=\frac{30\times 30}{59}=15.25\] So, least number of planks = 16
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