The center of gravity coincides with the center of mass: Select one:
O a. if the center of mass is at the geometrical center of the body
O b. if the body has a uniform distribution of mass
O c. never
O d. if the acceleration due to gravity is uniform over the body
o e. always

(a) assume the equation x = at^3 + bt describes the motion of a particular object, with x having the dimension of length and t having the dimension of time. determine the dimensions of the constants a and b. (use the following as necessary: l and t, where l is the unit of length and t is the unit of time.) (b) determine the dimensions of the derivative dx/dt = 3at^2 + b. (use the following as necessary: l and t, where l is the unit of length and t is the unit of time.)