If a force F1 = 6H is applied to the rubber harness, then the elongation of the harness will be l1 = 1 cm.

If a force F1 = 6H is applied to the rubber harness, then the elongation of the harness will be l1 = 1 cm. How much the tourniquet will lengthen if a force F2 = 18H is applied to it.

F1 = 6H
l1 = 1 cm = 0.01 m
F2 = 18 H
l 2 -?
F1 = l1 * k1, where k1 is the stiffness of the rubber band k1 = F1 / l1
F2 = l2 * k2, k2 = F2 / l2
k1 = k2, since the rubber band is the same
F1 / l1 = F2 / l2

l2 = F2 * l1 / F1
l2 = 18 * 0.01 / 6 = 0.03 m = 3 cm
Answer: the tourniquet will lengthen by 3 cm