In the figure a fastidious worker pushes directly along the handle of a mop with a force upper f overscript right-arrow endscripts. the handle is at an angle θ = 44° with the vertical, and μs = 0.68 and μk = 0.32 are the coefficients of static and kinetic friction between the head of the mop and the floor. ignore the mass of the handle and assume that all the mop's mass m = 0.64 kg is in its head.
(a) if the mop head moves along the floor with a constant velocity, then what is f?
(b) if θ is less than a certain value θ0, then upper f overscript right-arrow endscripts (still directed along the handle) is unable to move the mop head. find θ0.