2. Inclined Plane Problems
Understand ∑F = ma & how to resolve into x,y components in the tilted coordinate system!!
Tilted coordinate
system: Convenient,
but not necessary.

3. FGy= FGcos(θ) = -mgcos(θ) You MUST understand this case to
By trigonometry: FGx= FGsin(θ) = mgsin(θ)
FGy= FGcos(θ) = -mgcos(θ)
You MUST
understand this
case to
understand the
case with friction!!
By geometry, the
2 angles marked
θ are the same!
FG = mg

4. Example Is the normal force FN equal & opposite to the weight FG?

5. Example ∑F = ma  FN = mgcosθ
x: mgsinθ – Ff = ma
y: FN - mgcosθ = 0
Friction: Ff = μkFN
NOTE:
 FN = mgcosθ
 mg
THE NORMAL FORCE IS NOT EQUAL TO THE WEIGHT!!!