# 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.