Download Physics Name: Friction and Inclined Plane Notes Two types of

Physics
Name: ________________________
Friction and Inclined Plane Notes
Two types of Friction:
1. Static Friction Force (Fs) – keeps a stationary object from moving
2. Kinetic Friction Force (Fk) – acts opposite the motion of a moving object
Fs > Fk
Friction depends on the following:
1. types of surfaces in contact, texture
2. normal force
Coefficient of Friction (µ) – a number that describes the types of surfaces in contact
µs = coefficient of static friction
chart p. 138
µk = coefficient of kinetic friction
Maximum static friction force:
Kinetic friction force:
When doing friction problems:
1. FN = Wt (if the surface is horizontal and no other vertical forces act on the
object.)
2. Fs,max = Fapplied if object is just starting to move
3. Fk = Fapplied
if object is moving with a constant velocity
Inclined Planes without Friction:
FN = F⊥ =
ΣF =
Example: A 5 N box slide down a 30° inclined plane. What is the box’s acceleration?
Inclined Planes with Friction:
(A)
ΣF = F// - Fk
FN = F⊥
Example: A 5 kg object slides down a 41° incline. If the coefficient of kinetic friction is
0.28, find the acceleration of the object.
(B) If object “just begins to slide”
Fs.max = F//
FN = F⊥