Question: A rectangular Sitka spruce beam, dressed size 8 by 12 in with a 12-ft simple span, carries a uniform load of 1600 lb/ft. What is the unit horizontal shearing stress at the following points?
a. At the neutral axis and at the end of the beam
b. Four inches from the neutral axis and 1 ft from the support
c. Two inches from the neutral axis and at a quarter point.