Forces & Friction Formulas Page 1 of 1 FDHS Physics
Forces & Friction - Formula Sheet
Newton’s 2nd Law
o Fnet = mass x acceleration = m * a
o If force is gravitational (Fg or weight↓),
Weight = mass * gravitational acceleration
Weight = m * g
Kinematic Equations (general)
o vf = v0 + at
o vf2 = v02 + 2ad
o d = v0t + ½ at2
Inclined Plane ( ) - F|| vs Ff
o F|| down plane (causing motion) = mg sin
o Ff up plane (friction force opposing motion) = mg cos
Friction
o Coefficient = Force of friction (Ff) (0 < <1)
Normal force (FN)
Ff = FN
Net Force (Fnet)
o Flat plane: Fnet = Fa – Ff = Fa – μmg
o Inclined plane: Fnet = F|| - Ff = mgsinθ = μmgcosθ
Pressure
o P = Applied force
area of application
o P = F/A (= mg/A when using a gravity or weight model)
Conversion
o cm2 x 10-4 = m2
o mm2 x 10-6 = m2
Units
o Force - Newtons
o Pressure - N/m2 or Pascals (Pa)