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Since the particle's orientation at the time of image capture has a large influence on all these parameters, the equivalent spherical diameter is obtained by averaging a large number of measurements, corresponding to the different particle orientations. Of note, the ISO standards providing guidance for performing particle size determination by ...
The same explanation without buoyancy or center of mass arguments: As a larger particle moves upward, any motion of smaller particles into the spaces underneath blocks the larger particle from settling back in its previous position. Repetitive motion results in more smaller particles slipping beneath larger particles.
A free particle with mass in non-relativistic quantum mechanics is described by the free Schrödinger equation: (,) = (,) where ψ is the wavefunction of the particle at position r and time t . The solution for a particle with momentum p or wave vector k , at angular frequency ω or energy E , is given by a complex plane wave :
Deposition due to Brownian motion obeys both Fick's first and second laws. The resulting deposition flux is defined as J = n D π t {\textstyle J=n{\sqrt {\frac {D}{\pi t}}}} , where J is deposition flux, n is the initial number density , D is the diffusion constant and t is time.
the mass–energy equivalence formula which gives the energy in terms of the momentum and the rest mass of a particle. The equation for the mass shell is also often written in terms of the four-momentum ; in Einstein notation with metric signature (+,−,−,−) and units where the speed of light c = 1 {\displaystyle c=1} , as p μ p μ ≡ p ...
(If the position vector of a point particle varies with time, it will trace out a path, the trajectory of a particle.) Momentum space is the set of all momentum vectors p a physical system can have; the momentum vector of a particle corresponds to its motion, with dimension of mass ⋅ length ⋅ time −1 .
Quantum chemistry computer programs are used in computational chemistry to implement the methods of quantum chemistry.Most include the Hartree–Fock (HF) and some post-Hartree–Fock methods.
One of the results from the band theory of solids is that the movement of particles in a periodic potential, over long distances larger than the lattice spacing, can be very different from their motion in a vacuum. The effective mass is a quantity that is used to simplify band structures by modeling the behavior of a free particle with that mass.