The speed of a transverse wave on a string of linear mass density μ under tension T is

1. Tension provides the restoring force for a stretched string. 2. Linear mass density μ (mass per unit length) provides the inertia. 3. Wave speed v = √(T / μ), analogous to v = √(force/inertia). 4. So doubling tension increases v by √2; doubling μ decreases v by √2. _Source: syllabus Physics, Ch 14 "Waves", §14.4_