Gravitation Question 147
Question: How much energy will be necessary for making a body of 500 kg escape from the earth $ [[g=9.8,m/s^{2}] $ , radius of earth $ [=6.4\times 10^{6},m]] $ [MP PET 1999]
Options:
A) About $ [9.8\times 10^{6},J] $
B) About $ [6.4\times 10^{8},J] $
C) About $ [3.1\times 10^{10},J] $
D) About $ [27.4\times 10^{12},J] $
Show Answer
Answer:
Correct Answer: C
Solution:
Potential energy of a body at the surface of earth $ [PE=-\frac{GMm}{R}=-\frac{gR^{2}m}{R}] $ = $ [-mgR] $ = $ [-500\times 9.8\times 6.4\times 10^{6}] $ = $ [-3.1\times 10^{10}J] $ So if we give this amount of energy in the form of kinetic energy then body escape from the earth.
