Acord is used to vertically lower an initially stationary block of mass m kg at a constant downward acceleration of g/4. the block has fallen a distance d. (use any variable or symbol stated above as necessary.) (a) find the work done by the cord's force on the block. wf = 3mgd 4 incorrect: your answer is incorrect. (b) find the work done by the weight of the block. wg = (c) find the kinetic energy of the block. k = (d) find the speed of the block. v =