Chapter 4. Translational Equilibrium and Friction Solutions

4-1.  Draw a free-body diagram for the arrangements shown in Fig. 3-18.  Isolate a point where the important forces are acting, and represent each force as a vector.  Determine the reference angle and label components.

4-3 Three identical bricks are strung together with cords and hung from a scale that reads a total of 24 N.  What is the tension in the cord that supports the lowest brick?  What is the tension in the cord between the middle brick and the top brick?                  

Solution:  Each brick must weight 8 N.  The lowest cord supports only one brick,

   whereas the middle cord supports two bricks.

4-4 A single chain supports a pulley whose weight is 40 N.  Two identical 80-N weights are then connected with a  cord that passes over the pulley.  What is the tension in the supporting chain?  What is the tension in each cord?
 Each cord supports 80 N, but chain supports everything.

4-11 A wire is stretched between two poles 10 m apart.  A sign is attached to the midpoint of the line causing it to sag vertically a distance of 50 cm.  If the tension in each line segment is 2000 N, what is the weight of the sign?  (h = 0.50 m)

   tan f = (0.5/5) or  f = 5.71⁰ ;    2(2000 N) sin f = W

W = 4000 sin 5.71;