Which one of the following approximations gives the acceleration due to gravity g′ at a small height h (h≪R) above the Earth’s surface, where g is the surface value and R is Earth’s radius?
a) g′=g(1−Rh)
b) g′=g(1−2Rh)
c) g′=g(1−R2h)
d) g′=g(1−R22h2)