Inclined Plane Problems

1
Inclined Plane Problems
2
Forces Acting on the Object
y
Note The applied force and the force of
friction can be in either direction as long as
the friction force is opposite to the motion.
Fapplied
Fnormal
Ffriction
WX
Wy
?
W
WX
x
?
Remember Weight W FgFwmg (different
teachers may use different symbols )
3
Useful Equations for Inclined Plane Problems

• Explanation of Symbols
• Fnet net force
• m mass
• w weight (force)
• Ff friction
• ? coeff. of friction
• FN normal force (perpendicular force
  applied by surface)

• Formulas
• Fnet ?Fma
• Wmg
• Wxmg sin ?
• Wymg cos ?
• Ff? FN

4
Problems With No Acceleration

• When the object on the plane does not have any
  acceleration, then the forces acting on the
  object must be equal to zero.

?FxFapplied-Ffriction -Wxma 0 (a0)
y
Fapplied
?Fy Fnormal-Wyma0 (a0)
Fnormal
Ffriction
WX
Wy
W
x
?
WX
5
Problems With Acceleration
Fnet ma ?FxFapplied -Ffriction -Wxma
?Fy Fnormal-Wyma0 (a0, no motion along the
y-axis)
y
Fapplied
Fnormal
Ffriction
WX
Wy
W
x
?
WX
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Friction
Friction depends on the roughness of the surfaces
and the force pushing them together. The
coefficient of friction (µ) is determined by the
texture of the surfaces in contact. The normal
force is the force pushing the 2 surfaces
together There are 2 types of friction, static
and kinetic (sliding) Static friction is the
frictional force that an object must overcome to
start its motion. (µis higher for static
friction) Kinetic (or sliding) friction is the
force opposing the motion of an object. The
formula for finding friction is FfµFN