1. 5. Types of forces Remember the 4 basic interactions: Common forces:
Gravity
Electromagnetic
Weak (nuclear)
Strong (nuclear)
Common forces:
Weight (W = mg)
Normal force (N) (90° from a supporting surface)
Force of friction (Fμ = μN), μ is the coefficient of friction
Tension force (T) (in a supporting string)

2. Solving force problems:
List the initial values
Draw a FBD (when possible)
Is there acceleration (ΣF = ma) or not (ΣF=0)?
Study the forces in x- and y-directions separately or use a triangle (if there are forces in three directions)
Solve: 4.5, 4.7, 4.8, 4.9 (4.10) on p. 20
Solve: 5.1, 5.2, 5.5, 5.7, 5.8 on p. 24