A) 1000 N
B) 500 N
C) 250 N
D) 125 N
Correct Answer: C
Solution :
Key Idea: Value of acceleration due to gravity decreases on going below the surface of the earth. Weight (w) of a body is defined as product of mass (m) and acceleration due to gravity (g) w = mg The value of g below the surface of earth at a distance h is given by \[={{\varepsilon }_{0}}\,\,E_{rms}^{2}\] \[=8.85\times {{10}^{-12}}\times {{(720)}^{2}}\] \[=4.58\times {{10}^{-6}}J/{{m}^{3}}\] Given, \[{{10}^{-10}}s\] \[f=\frac{v}{v-{{v}_{s}}}f\] \[{{v}_{s}}\] \[v=320m/s,\,{{v}_{s}}=4m/s,\,f=240Hz\] Note: Value of g also decreases ongoing above the surface of earth, as follows \[f=\frac{320}{320-4}\times 240\]You need to login to perform this action.
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