1. A sound wave is moving at 340 m/s. If it has a wavelength of 0.63 m, what is its frequency?

2. A lightning flash is seen and thunder is heard three seconds later. If the speed of sound is 340 m/s and the speed of light is 3x10^8 m/s, how far away did the lightning strike?

3. What happens to the speed of ocean waves as they come close to shore? How can this be explained from what you've learned so far?

4. Sound travels faster through wood than through air. Sound also travels faster through helium than through air. Using the concepts of density and rigidity, explain these observations.

5. Even light moves slower when passing through a denser medium. The index of refraction for a material is the ratio of speed of light in a vacuum to the speed that light travels in the material. The index of refraction of glass is 1.33. If the speed of light in a vacuum is 3.0 x 10⁸ m/s, what is the speed of light in glass? (Use what you've learned to make sure your answer makes sense!