The acceleration due to gravity at the poles and the equator is gp and ge respectively. If the earth is a sphere of radius RE and rotating about its axis with angular speedω, then gp-ge is given by

Acceleration due to gravity at a place of latitude λ due to the rotation of earth isg' = g-REω2cos2λAt equator, λ = 00, cos00 = 1∴ g' =ge =g-Rgω2At poles, λ = 90°, cos 90° = 0∴ g' = gp =g∴ gp-ge = g-(g-REω2) = REω2