Note: There are some errors in the overheads shown in the following
three images. Corrected versions are available below.
It is a useful exercise to compare the two versions and to consider the
mistakes (in particular, the free body diagram and equilibrium equations
have been handled inconsistently, and additionally there have been
"slip of the pen" errors in the algebra).
It is also useful to work through problems like this in a symbolic
fashion (i.e. without substituting in actual numbers until the very
end). This has been done for problem 3-91 in the next two pages:
