Three forces in balance, ex. 4, p. 54
 
You can use the critical fact, net force is zero, to deduce the size and direction of the unknown third force.  This is like Mr. Sherlock Holmes making the elementary deduction of what must be true if the three forces all balance.
 
Wednesday, July 4, 2007
 
 
 
 
 
 
 
Relationship of three forces, scientific detective work.