The height vertically above the earth's surface at which the acceleration due to gravity becomes 1 % ofits value at the surface is [WB JEE 2011]

Acceleration due to gravity at a height h from earth's surface,g'=GM(R+h)2Given,    g'=1% of g=g100⇒  g100=GM(R+h)2(R+h)2100=GMg or (R+h)2100=R2    ∵g=GMR2∴  R+h=10R      h = 9Rwhere, R is the radius of the earth.