# Wave Motion - Mission WM3 Detailed Help

 A sound wave having a frequency of 261 Hz is observed to travel 341.0 meters in 1.0 seconds. What is the speed (in m/s) of the sound wave?   (Note: Your numbers are selected at random and likely different from the numbers listed here.)
 The speed of a wave refers to how fast it travels through a medium. By definition, it is the distance traveled per unit of time. Speed = distance traveled / time of travel = d / t
 It is not uncommon for a student of physics to be insistent that all the information given in a problem is required to obtain the answer. But don't be fooled! Physics problems are mostly about (or at least should be mostly about) making right choices between what is important and unimportant in a given situation. Physics problems like this one are more than plug-and-chug exercises; they are tests of whether you understand the concepts clearly.   There are three pieces of quantitative information given in this question. Only two of the pieces are of importance. Deciding on which two pieces are important demands that you understand the two equations for wave speed (see Formula Frenzy sections). Using the equation demands that you know both frequency and wavelength values. While the frequency is known as recognized by its characteristic unit (Hz), the wavelength is not known. The 341.0 m is the distance traveled by the wave in the 1.0 second of travel. Knowing the distance traveled and the time of travel means that the v = d /t equation should be used to determine wave speed.
 The speed (v) of a wave can be calculated from knowledge of the wavelength (W) and the frequency (f) of the wave. The formula is   v = f • W