Equations & Constants

This page contains equations and constants that you may find useful during this course. You are welcome to print a copy of this page and use it during tests but you may not annotate this page in any way if you are going to use it in a test situation - it is your responsibility to understand these equations and their limitations...

Equations

  • vav = (x2 - x1) / (t2 - t1) = Δx / Δt
  • aav = (v2 - v1) / (t2 - t1) = Δv / Δt

The next 5 equations assume that the acceleration is constant and that motion is linear:

  • a = (v - v0) / t
  • v = v0 + a t
  • Δx = ½ (v + v0) t
  • Δx = v0 t + ½ a t 2
  • v2 = v02 + 2 a Δx

  • Fnet = ma
  • W = mg
  • Ffr <= µs FN
  • Ffr max = µs FN
  • Ffr = µk FN
  • µ = tan θ
  • component of weight perpendicular to inclined plane = FN = mg sin θ
  • component of weight parallel to inclined plane = mg cos θ
  • Fcent = mv²/r
  • f = v/2πr
  • T = 1/f = 2πr/v
  • Fgrav = Gm1m2/r²
  • W = F d = Fd cos θ
  • KE = ½ mv²
  • Wnet = Fnet d = ΔKE = ½ mv2² - ½ mv1²
  • GPE = PEG = mgh
  • PEel = ½ kx²
  • k = -F/x
  • P = W/t = E/t
  • p = m v
  • Fnet t = Δp
  • v = fλ
  • T = 1/f
  • i = r
  • I = Q/t
  • V = E/Q
  • V = IR
  • Rseries= R1 + R2 + …
  • 1/Rparallel = 1/R1 + 1/R2 + …
  • For two resistors in parallel:
  • Rparallel = R1R2/(R1+R2)
  • P = VI = I²R = V²/R

Constants

  • g = 9.81 m / s² on planet Earth (you may take g = 10 m / s² unless told otherwise)
  • G = 6.67 x 10-11 m3 kg−1 s−2
  • Density of water = 1000 kg/m3
  • Density of air at atmospheric pressure and 20°C = 1.2 kg/m3
  • Speed of light in a vacuum = 3.0 x 108 m/s
  • 1 coulomb (1C) is the charge on 6.25 x 1018 protons.