A block of mass M is pulled along a horizontal frictionless surface by a
rope of mass m, as shown. A horizontal force P is applied to one end of
the rope. (a) Show that the rope must sag, even if only by an imperceptible
amount. Then, assuming that the sag is negligible, find (b) the acceleration
of the rope and block, (c) the force that the rope exerts on the block, and (d) the tension in
the rope at its midpoint.
The Attempt at a Solution
To be honest I don't have a clue on where to start any segment of this problem... Especially part a and part d. Any help you guys can offer would be greatly appreciated. If you need to see the image I'm sure I could upload it somewhere (basically it's just a block M being pulled by a rope m in the right horizontal direction by some force P).