Mersenne's laws govern the construction and operation of string instruments, such as pianos and harps, which must accommodate the total tension force required to keep the strings at the proper pitch. Lower strings are thicker, thus having a greater mass per length. They typically have lower tension.
Mersenne's laws govern the construction and operation of stringed instruments, such as pianos and harps, which must support the total tension force necessary to maintain the proper pitch. Thicker strings have a greater mass per unit length, resulting in lower tension.