rocket equation

Short definition from Wiktionary

Noun

1. 1
   The equation for how much delta-v a rocket produces: Δv = vₑ ln(m₀/m₁); where Δv is delta-v, vₑ is effective exhaust velocity, ln is the natural log function, m₀ is initial mass of the rocket, and m₁ is final mass of the rocket.