View Policies Current Attempt in Progress A cord is used to vertically lower an initially stationary block of mass M = 2.7 kg at a constant downward acceleration of g/4. When the block has fallen a distance d = 2.1 m. find (a) the work done by the cord's force on the block. (b) the work done by the gravitational force on the block. (c) the kinetic energy of the block, and (d) the speed of the block. (Note : Take the downward direction positive) (a) Number 42 Units (b) Number 26 Units (c) Number i -15 Units J (d) Number i Units eTextbook and MediaA helicopter lifts a 71 kg astronaut 11 m vertically from the ocean by means of a cable. The acceleration of the astronaut is g/16. How much work is done on the astronaut by (a) the force from the helicopter and (b) the gravitational force on her? Just before she reaches the helicopter, what are her (c) kinetic energy and (d) speed? (a) Number ! Units (b) Number -7.763 Units (c) Number i ! Units (d) Number i Units m/s