72. (a) A small segment of the rope has mass and is pulled down by the gravitational force of the Earth. Equilibrium is reached because neighboring portions of the rope pull up sufficiently on it. Since tension is a force alongthe rope, at least one of the neighboring portions must slope up away from the segment we are considering. Then, the tension has an upward component which means the rope sags. (b) The only force acting with a horizontal component is the applied force GF. Treating the block and rope as a single object, we write Newton’s second law for it: F= (M+ m)a,whereais the acceleration and the positive direction is taken to be to the right. The
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This note was uploaded on 05/17/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.