Free body diagrams and FRICTION How do I calculate forces accurately?

FBD – The Best Motion Picture  Box  Arrow  Label 6.0 N2.0 N Note: the 6.0N arrow is about 3 times longer than the 2.0N arrow

Which way does the object move?  Are the forces balanced?  Where does the imbalance lie? 6.0 N2.0 N

F net = F 1 +F 2  -6.0N + 2.0N = F net  -4.0N = F net 6.0 N2.0 N -4.0N

Norm L. Force The Balancer

Normal forces oppose applied forces (like gravity).  We don’t fall through our chairs thanks to the normal force.

Friction eats up some of the applied force.  Static friction – when you are trying to start pushing something.  Kinetic friction – when it is already in motion.

Friction eats up some of the applied force.  (F f ) = u(F n )