why is a pulse on a string considered to be transverse
Transverse wave Transverse waves are waves that are oscillating perpendicularly (at a right angle) to the direction of propagation. If you anchor one end of a ribbon or string and hold the other end in your hand, you can create transverse waves by moving your hand up and down. Notice though, that you can also launch waves by moving your hand side-to-side. This is an important point. There are two independent directions in which wave motion can occur. In this case, these motions are the Y and Z directions mentioned above, while the wave propagates away in the X direction. The other type of waves is the longitudinal wave, which oscillates in the direction of its propagation.
String section The string section is the largest body of a single instrument category in the standard Classical orchestra. It normally consists of the first violins, the second violins, the violas, the cellos, and the double basses (or basses). The first and second violinists play the same types of instruments; the difference between the two sections is in the types of musical lines that are typically given to each section. The first violins are generally given the melody or higher-pitch musical lines, whereas the second violins generally play a part that is lower in pitch than the first violins. The second violins may play a harmony part, a countermelody or an accompaniment passage. In discussions of the instrumentation of a musical work, the phrase "the strings" or "and strings" is used to indicate a string section as just defined. An orchestra consisting solely of a string section is called a string orchestra. Smaller string sections are used in jazz, pop and rock music arrangements and in musical theatre pit orchestras.