A) \[\text{3 }km/hr\]
B) \[4\text{ }km/hr\]
C) \[\text{5 }km/hr\]
D) \[\text{2 }km/hr\]
Correct Answer: A
Solution :
\[{{V}_{mr}}=5\,km/hr,\] \[t=15\,\min \] \[t=\frac{d}{\sqrt{V_{mr}^{2}-V_{r}^{2}}}\] \[\Rightarrow \]\[\frac{15}{60}=\frac{1}{\sqrt{25-V_{r}^{2}}}\] \[\Rightarrow \] \[4=\sqrt{25-V_{r}^{2}}\] \[\Rightarrow \]\[V_{r}^{2}=25-16\] \[\Rightarrow \]\[V_{r}^{2}=9\]\[\Rightarrow \] \[{{V}_{r}}=3\,km/hr\]You need to login to perform this action.
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