http://www.ck12.org Chapter 5. Forces in Two Dimensions
walk or a car tire turns, the force of friction opposes the direction your foot or the tire attempts to move. In
the latter cases it is the static friction that is responsible for moving you and the car forward.- Do not confuse the coefficient of friction with the force of friction. The coefficient of friction is not a force!
- In solving problems on inclined planes, we usually place thex−axis along the plane so the acceleration is
coincident with thex−axis. - A sliding object on a frictionless inclined plane has accelerationa=gsinθand is subject to a normal force
FN=mgcosθ. - The magnitude of the centripetal acceleration isac=v
2
r and its direction is toward the center of the circle. - In solving static problems, it is useful to set up a coordinate system such that the object in equilibrium is at
the origin and then resolve all forces into components. Use∑Fx=0 and∑Fy=0 to generate two equations
with two unknowns.