I've ask this question twice her but I got different answer. Please tell me who's right

(They have the same answer on the radian but different number on the speed )

Topic: Angular Motion in a Plane

Question:

Earth rotates about its axis.It completes one rotation about its axis in one day(24hours). Angular speed (@) is angle rotated (0) per unit time((). Mathematically , @ = = - equation(1) Above formula can be reaaranged as 0 = ot -> equation(2) Linear speed (v) = angular speed (@) x Radius ofcircular path (R) - equation(3) Given : Radius of earth R = 6370kmAs we know it takes 24 hours to complete one rotation and angle rotated in one rotation is 2a radian. 2x radian By use of equation (1), angular speed of earth (@) = 24 hour radian / hour 12 By use of equation (2), angle rotated by a point on earth in 6 hours, 0 = radian / hour x (6hours) radian 12 2A po int on equator of earth moves in a circular path of radius equal to radius of earth. By use of equation(3) , Speed of a point on equator, VE radian / hour x(6370km) V = 1667.66km / hour 12 Angle rotated by a point on surface of earth in 6 hours is - radian and speed of a pointon equator is 1667.66km / hour.Through how many radians does a point on the Earth's surface move in 6.00 h as a result of the Earth's rotation? What is the speed of a point on the equator? Take the radius of the Earth to be 6370 km