PHYS 1080 Lecture Notes - Lecture 17: Centrifugal Force, Terminal Velocity, Globular Protein
5 Dec 2016
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In many cases, the probability that some state" exists (e. g. a particle with energy e) is given by boltzmann"s distribution: P1 = n1/n0 = exp [ - e1/k. bt] P1/p2 = n1/n2 = exp [-(e1 - e2)/k. bt] To get partial distribution, particles must have the right density (very close to that of the suspending uid) Distribution arises from the nearly balanced but competing energies: gravitational: u = (p - p. l)vgh, thermal: k. bt. An object will fall in a liquid if its density is larger than that of the suspending medium. Frictional (drag) force: depends on the velocity (f. frict = v, introduce proportionally constant f, known as the friction factor. For a sphere, einstein showed that when a= 0, can solve for terminal velocity: How long would it take a spherical protein molecule (molar mass 2. 0x10^6 g/mol) to settle 3. 0 mm in water: m= m/n. a. 4/3 pi r^3 = 2. 55x10^-24 m^3 r= 8. 47x10^-4: vt= 2r^2g/9n(p - p. l)
