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The speed of sound is given by the Newton-Laplace equation: $$ v = \sqrt{\frac{K}{\rho}} $$ where $K$ is the bulk modulus (i.e. a measure of stiffness) and $\rho$ is the density. The physical interpretation of this is fairly obvious. Stiffer substances recoil faster from a displacement so increasing the stiffness increases the speed of sound. Heavier ...


The speed of sound depends on the average speed the molecules are moving. Increasing temperature means increasing the average velocity of the gas molecules, hence increasing the speed of sound. And vice versa. Wavelength is related to the speed of sound and frequency


In addition to the other answers, "bright light can never hurt your eyes" has to be false -- you up the intensity of the light enough, and the energy density can get arbitrarily high. In principle, it's possible to have light so bright that it collapses to a black hole. Before then, you'll get pair production in the light beam.


Here is a slightly different take on this using the boundary conditions for electromagnetic fields at an interface. A key boundary condition, that is derived from Faraday's law, is that the component of the E-field tangential to the boundary must be continuous. So take an EM wave travelling at normal incidence with the electric field solely in a direction ...


If you have a small diapragm moving slowly then the air will just flow around it and you won't get any appreciable pressure rise in front of the diaphragm. That means there won't be any longitudinal pressure waves (i.e. sound waves) generated normal to the diaphragm surface. If you now make the diaphragm larger the air has farther to move to get to the ...

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