The value of on the surface of earth is smallest at the equator because 

a) 
The centripetal force is maximum at equator 
b) 
The centripetal force is least at equator 
c) 
The angular speed of earth is maximum at equator 
d) 
The angular speed of earth is least at equator 
The value of on the surface of earth is smallest at the equator because 

a) 
The centripetal force is maximum at equator 
b) 
The centripetal force is least at equator 
c) 
The angular speed of earth is maximum at equator 
d) 
The angular speed of earth is least at equator 
(c) Due to rotation of earth the effective acceleration due to gravity For a given point on the surface of earth decreases as increases. The angular speed of earth is maximum at equator hence, the value of on the surface of the earth is smallest. 