# Direction of the force of a mechanical wave

Currently, I am learning about mechanical waves in school, including sound and what-not. My teacher provided us with this formula for the energy per length of any given wave on a string: $$E/L = 2(π^2)(f^2)(A^2)μ$$ where $$E/L$$ is the kinetic energy per unit length, $$f$$ is frequency, $$A$$ is amplitude, and $$μ$$ is the linear density of the string. Being a basic introductory physics class, the teacher didn't get into the derivation of this formula, but more so just threw it at us. However, I noticed that $$E/L$$ has the same units as force $$(kg \cdot m/s^2)$$ so I was wondering if kinetic energy per unit length is another way of representing the force of a wave. Which way would this wave force point? Is it of any significance?

• Are you sure about the term "power" because power is not energy per unit length, which you correctly point out has units of force. Power has units of energy per unit time or force times velocity. Mar 14, 2020 at 1:36
• Whoops, yeah that's a mistake, thanks for pointing it out. Mar 16, 2020 at 19:16