A) 0.94 h
B) 0.80 h
C) 0.75 h
D) 0.64 h
E) 0.50 h
Correct Answer: D
Solution :
\[v=\sqrt{2gh}\] ...(1) After rebounce, \[{{v}^{2}}={{u}^{2}}-2gh\] \[\Rightarrow \] \[{{u}^{2}}={{v}^{2}}+2gh\] \[\therefore \] \[{{u}^{2}}=2gh\] ...(2) \[\therefore \] \[\frac{{{v}^{2}}}{{{u}^{2}}}=\frac{2gh}{2gh}\] \[\Rightarrow \] \[h=h\times \frac{{{u}^{2}}}{{{v}^{2}}}=h\times {{\left( \frac{80}{100} \right)}^{2}}\] \[=0.64\,h\]
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