Using the HO model to obtain the impact force of real climbing ropes as a function of fall height "h" and climber's weight "mg", one must know the experimental value for "E" of a given rope. However, rope manufacturers give only the rope’s impact force "F0" and its static and dynamic elongations that are measured under standard UIAA fall conditions: A fall height "h0" of 2 × 2.3 m with an available rope length "L0" = 2.6m leads to a fall factor "f0" = "h0/L0" = 1.77 and a fall velocity "v0" = ("2gh0")1/2 = 9.5 m/s at the end of falling the distance "h0". The mass "m0" used in the fall is 80 kg. Using these values to eliminate the unknown quantity "E" leads to an expression of the impact force as a function of arbitrary fall heights "h", arbitrary fall factors "f", and arbitrary gravity "g" of the form: