Prob 1.2.1: The good, the bad, and the free body

A weak solution

• There is no final free body diagram.
  • This is important in learning to visualize equilibrium.

• The final answer is not indicated.
  • This makes it difficult to evaluate the solution.

• There are calculation mistakes.
  • These might have been detected with a clear final free body diagram.

An adequate solution

Good points

• The final answer is highlighted.

• The process and equations are clear.

  Weak points

• Units are not indicated in the equations.
  • In this problem, it can be understood that the 20 indicates kilonewtons and the 3 indicates meters, however in a problem that included 20 kN forces and 20 m lengths, it would not be. Units are very important in avoiding errors, making the work readable to others, and in maintaining an physical understanding of what the equations represent.