We all know that sound travels in longitudinal waves but in some books, I have found that sound travels in the form of both longitudinal and transverse waves while passing through rocks. Can anybody explain this to me?
[Physics] Can sound travel in the form of transverse waves
acousticswavelengthwaves
Best Answer
The difference between a fluid and a solid is the following: fluid's have zero shear modulus, so they cannot carry a shear force, but solids have non-zero shear modulus, so they can carry shear force.
Fun little way to visualize this: let's say we line up a bunch of second graders on rectangular grid. Now we push one of the students along one row. That student will push the next student in the same row and so the push will move through the row. However, the students in the other rows are unaffected. That's how a fluid behaves.
Now we ask the students to hold hands with their neighbors in the adjacent rows. If we push one student, not only will the push travel through the same row, but since the student are holding hands with their neighbors, these kids will move as well, so the the push will also travel laterally along the columns through the other rows. That's how a solid behaves.
In a solid, molecules are "holding hands" with their neighbors, in fluid they do not. This enables transversal waves in a solid.
Of course, in reality all the second graders would fall over each other giggling hysterically. The branch of physics dealing with kids is neither solid mechanics nor fluid mechanics, but probably chaos theory.