Physics Question: Static Equilibrium?
The question is on this picture
http://edugen.wiley.com/edugen/courses/crs4957/halliday9118/halliday9088c12/image_n/nt0009-y.gif
The practice question was: "The figure gives six overhead views of a uniform rod on which two or more forces act perpendicularly to the rod. If the magnitudes of the forces are adjusted properly (but kept nonzero), in which situations can the rod be in static equilibrium?"
The answers are 'c', 'e', and 'f'.
I can't even begin to figure out why...
Why are these answers, the answers?
Thank you so much in advance!