In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

Mobility is related to the zeta potential, dielectric constant, and this quantity in the Smoluchowski equation. For gases, the variation of this quantity with temperature is given by Sutherland's formula. Measured with a Zahn cup, this quantity is squared in the Grashof number, and the ratio of this quantity to thermal diffusivity is the Prandtl number. When this quantity is zero, the Euler equations correspond to the NavierStokes equations. Reynolds number is the ratio of inertial forces to this quantity, which is constant for Newtonian fluids. Measured in poise [PWAHZ], this quantity is zero for superfluids. For 10 points, name this internal friction of a fluid that tends to resist its flow.
Science

After allying with the khan of Chagatai and taking part in campaigns in Transoxania, this ruler would lose a "muddy battle" against Ilyas Khodja, despite fighting alongside brother-in-law Husayn of Balkh. Becoming the head of the Barlas upon the death of Tughluk, this man annihilated Tokhtamysh and the Golden Horde at the Battle of the Terek River before he overwhelmed Sultan Mehmud's forces in seizing the Delhi Sultanate. Prior to his death and ultimate succession by Shah Rukh while planning an invasion of China, he defeated the Turks at the Battle of Ankara and captured Bayezid I. FTP, name this Mongol military leader who ruled in Central Asia during the 14th century from his capital of Samarkand.
History

In liquids and gases, the birefringence of light in the presence of a transverse one of these entities is known as the Cotton-Mouton and Voigt effects, respectively. Small ones can be measured by superconducting quantum interference devices. There are plateaus in the plot of the Hall voltage versus this quantity. Spectral lines are split in the presence of one of these in the Zeeman effect. The force on a current-carrying wire is equal to the product of current, wire length, and the magnitude of this field, which is measured in units of teslas. For 10 points, name this type of field that is created by a moving charge and whose lines are continuous, unlike electric fields.

Science