  We present near-infrared K-band images of 15 galaxies. We have performed a
Fourier analysis on the spiral structure of these galaxies in order to
determine their pitch angles and dust-penetrated arm classes. We have also
obtained rotation curve data for these galaxies and calculated their shear
rates. We show that there is a correlation between pitch angle and shear rate
and conclude that the main determinant of pitch angle is the mass distribution
within the galaxy. This correlation provides a physical basis for the
dust-penetrated classification scheme of Block & Puerari (1999).
