Note: problem difficulty is ranked using a star system.

• (*) One-star problems are fundamental to the unit, and can be done relatively quickly. Use these problems to introduce yourself to the material.

• (**) Two-star problems are more difficult, and require an understanding of one or two key concepts. Use these problems to test your understanding of the material.

• (***) Three-star problems are the most difficult, and require some creative thinking in addition to a deep familiarity with multiple key concepts. Use these problems to challenge yourself; if you can complete one of these, you’re on your way to mastering the material.

*Q13.1) A sound wave is travelling through air with a wavelength of 29cm. What’s the frequency of the wave?

*Q13.2) Describe (or sketch) the difference between a transverse and a longitudinal wave. Which type is a sound wave?

**Q13.3) A travelling wave is described by the function y = 6 sin( 2πt - 4πx ) with SI units.

a) Find the amplitude, period, frequency, wavelength, and speed of the wave.

b) Is the wave travelling in the positive or negative x-direction?

**Q13.4) Sketch snapshots of the wave from Q13.3 at the following points in time:

a) t = 0

b) t = 0.25

c) t = 0.5

**Q13.5) Sketch snapshots of the wave from Q13.3 at the following points in space:

a) x = 0

b) x = 0.125

c) x = 0.25

*Q13.6) If the wave from Q13.3 were to reflect off a wall, what equation would describe the reflected wave?

**Q13.7) The following is a snapshot of a sound wave in air, travelling in the +x-direction. What’s the equation that describes it?