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ρ p is the mass density of the sphere [kg/m 3] ρ f is the mass density of the fluid [kg/m 3] g is the gravitational acceleration [m/s 2] Requiring the force balance F d = F e and solving for the velocity v gives the terminal velocity v s.
The microscopic origin of contact forces is diverse. Normal force is directly a result of Pauli exclusion principle and not a true force per se: Everyday objects do not actually touch each other; rather, contact forces are the result of the interactions of the electrons at or near the surfaces of the objects. [1]
This theory is exact for the situation of an infinite friction coefficient in which case the slip area vanishes, and is approximative for non-vanishing creepages. It does assume Coulomb's friction law, which more or less requires (scrupulously) clean surfaces. This theory is for massive bodies such as the railway wheel-rail contact.
kilogram per cubic meter (kg/m 3) diameter: meter (m) distance: meter (m) direction: unitless impact parameter meter (m) differential (e.g. ) varied depending on context differential vector element of surface area A, with infinitesimally small magnitude and direction normal to surface S
Frictional contact mechanics emphasizes the effect of friction forces. Contact mechanics is part of mechanical engineering . The physical and mathematical formulation of the subject is built upon the mechanics of materials and continuum mechanics and focuses on computations involving elastic , viscoelastic , and plastic bodies in static or ...
There are two main descriptions of motion: dynamics and kinematics.Dynamics is general, since the momenta, forces and energy of the particles are taken into account. In this instance, sometimes the term dynamics refers to the differential equations that the system satisfies (e.g., Newton's second law or Euler–Lagrange equations), and sometimes to the solutions to those equations.
The speed-dependence of the friction force is linear (()) at very low speeds (Stokes drag) and quadratic (()) at large speeds (Newton drag). [8] The transition between these behaviours is determined by the Reynolds number , which depends on object speed and size, density ρ {\textstyle \rho } and dynamic viscosity η {\textstyle \eta } of the ...
Churchill equation [24] (1977) is the only equation that can be evaluated for very slow flow (Reynolds number < 1), but the Cheng (2008), [25] and Bellos et al. (2018) [8] equations also return an approximately correct value for friction factor in the laminar flow region (Reynolds number < 2300). All of the others are for transitional and ...