A) 0.2 km
B) 0.4 km
C) 0.5 km
D) 0.3 km
E) None of the above
Correct Answer: E
Solution :
(*) If block to come to rest after 2m. So, \[d=\frac{{{u}^{2}}}{2a}\] \[a=\mu g=0.05\times 10=0.5m/{{\sec }^{2}}\] \[{{u}^{2}}=2\times 2\times 0.5=2\] \[u=\sqrt{2}m/\sec \]by momentum conservation \[\sqrt{2}\left( 10+50\times {{10}^{-3}} \right)=\left( 50\times {{10}^{-3}} \right)\times V\] approximately \[\frac{\sqrt{2}\times 10}{50\times {{10}^{-3}}}=V\] \[V=200\sqrt{2}m/\sec \]so \[\frac{V}{10}=20\sqrt{2}\] to get \[V=20\sqrt{2}m/\sec \] \[{{V}^{2}}=2gh\] \[h=\frac{800}{20}=40m\]You need to login to perform this action.
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