A) \[10.6\,km/s\]
B) \[0.106\,km/s\]
C) \[1.06\,km/s\]
D) zero
Correct Answer: A
Solution :
Work done in going from a distance \[{{r}_{1}}\] to a distance \[{{r}_{2}}\]away from centre of the earth, by a body of mass m, is, \[W=GMm(1/{{r}_{1}}-1/{{r}_{2}}),\] For our case we should have \[1/2m{{v}^{2}}=GMn[(1/{{R}_{e}})-(1/10{{R}_{e}})]\] \[=(GMm/{{R}_{e}})\times (9/10)\] \[v=\sqrt{{}}[(2GM/{{R}_{e}})\times (9/10)]=\sqrt{{}}(9/10)\times \]escape velocity \[\sqrt{{}}(9/10)\times 11.1km/s=10.6km/s\]
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