A) 4.8 m/s
B) 3.6 m/s
C) 2.4 m/s
D) 1.2 m/s
Correct Answer: C
Solution :
Let the velocity of father \[={{v}_{1}}\] According to the question, \[{{v}_{i}}=\frac{1}{2}{{K}_{son}}\] Final velocity of the father \[{{v}_{t}}=({{v}_{1}}+1.0)\,\,m/s\] Then, \[{{K}_{t}}={{K}_{son}}\] \[{{K}_{i}}=\frac{1}{2}{{K}_{t}}\] \[{{K}_{i}}=\frac{1}{2}\left[ \frac{1}{2}m\,{{({{v}_{i}}+1.0)}^{2}} \right]\] \[{{K}_{i}}=\frac{1}{4}m\,(v_{i}^{2}+1+2{{v}_{i}})\] \[\frac{1}{2}mv_{i}^{2}=\frac{1}{4}m\,(v_{i}^{2}+1+2{{v}_{i}})\] \[v_{i}^{2}=\frac{v_{i}^{2}}{2}+\frac{1}{2}+{{v}_{i}}\] \[v_{i}^{2}-{{v}_{i}}-\frac{1}{2}=0\] \[v_{i}^{2}-2{{v}_{i}}-1=0\] \[{{v}_{i}}=2.4\,m/s\]
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