Impulse (Relative)A measure of the efficiency of a rocket engine. Similar to Specific Impulse, it is defined as the Total Impulse divided by the mass of the propellants. A little dimensional juggling shows that this gives the same units as velocity (ft/sec or m/sec) hence is sometimes called "Effective Exhaust Velocity." How quickly the reaction mass leaves the nozzle is a good measure of efficiency. What You Can Do 

