For 10 points, name this number of space-time dimensions.
For a tube open at one end and closed at the other, the wavelength of the first harmonic equals the length of the pipe times this number. In a fluid, the volume flow rate is proportional to the radius raised to this power in Poiseuille's [pwah-ZWEEZ] law. Rounded to the nearest whole number of degrees Celsius, the density of water is greatest at this temperature. An atom's mass number decreases by this value when alpha decay occurs. Including the zeroth, there is this number of laws of thermodynamics. For 10 points, name this number of space-time dimensions.
For a tube open at one end and closed at the other, the wavelength of the first harmonic equals the length of the pipe times this number.
four [accept obvious equivalents, such as fourth] 