Calculate the energy needed for moving a mass of 4kg from the centre of the earth to its surface (in multiple of 108 joule), if radius of the earth is 6400 km and acceleration due to gravity at the surface of the earth is g=10m/s2
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Solution
Given:
Mass(m)=4kg
Radius of Earth(R)=6400km
Acceleration due to gravity(g)=10m/s2 Ui=−3GMm2R…(i) Uf=−GMmR…(ii) ΔU=Uf−Ui ΔU=GMm2R=−mgR2
Hence, by putting the values we get, ΔU=4×10×6.4×1062 ΔU=1.28×108J
Final Answer: 1.28