The speed of sound varies according to the material through which it travels. Sound travels at 5.4 x 109 cm/s through rubber and at 1.97 x 10^ ft/s through granite. Calculate each of these speeds in
m/s.

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?