1 / 20

States of matter

States of matter. Solid:. Fluid:. Liquid Gas Plasma. Crystalline Amorphous. z.  zz.  yz.  xz.  zy.  zx.  yy.  yx.  xy. y.  xx. x. internal interaction.

roanna-mclaughlin
Download Presentation

States of matter

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. States of matter Solid: Fluid: • Liquid • Gas • Plasma • Crystalline • Amorphous

  2. z zz yz xz zy zx yy yx xy y xx x internal interaction In a medium, a set of parameters leading to the forces exerted on an infinitesimal cube element within the medium, is called the stress tensor. where is the i-th scalar component of the force exerted on the j-th wall of the cube and dA is the area of one wall. The SI unit of stress is the pascal (Pa). Note: Only six independent components.

  3. z dyz dzz dxz dzy dyy y dxy dxx dzx dyx x deformation The deformation is described by a strain tensor where d(xi)j is the displacement of the j-th corner in the i-th direction, and is the size of the cube (initial).

  4. Within certain limits, the differential change in stress, caused by external forces exerted on the medium, is a linear function of the differential strain. or Hook's law The proportionality tensor is called a modulus.

  5. z The external forces, applied along a single line to two opposite sides of the rod, cause a uniform stress dF dL L Coefficient Y is called Young's modulus. y -dF x tension We can often approximate a finite change in the related quantities using the above differential relation

  6. z The external forces are applied along a single line to two opposite sides F L L The nonzero component of compressive stress is called uniaxial pressure (P) y -F x compression (uniaxial pressure)

  7. z Tangential external forces applied to two opposite sides of the object cause a shear stress dy h d dF y -dF x Shear stress Coefficient S is called the shear modulus. Comment 1. Fluids in rest do not create shear stress. Comment 2. The occurrence of a velocity dependent stress in a moving fluid is called viscosity.

  8. z dF Under hydrostatic pressure, all shearing components of the stress are zero and all compressive components of stress are equal. dF dF dF dF x y Hydrostatic pressure Hook’s law:

  9. F0 F0 h W In a gravitational field, pressure in fluids depends on the pressure created by an external force and the depth in the fluid F(h) fluid at rest P0 for uniform density: P(h)

  10. F1 Pascal's principle A change in the pressure applied to an enclosed (incompressible) fluid is transmitted undiminished to every portion of the fluid. F2 Hydraulic Press: A1 A2

  11. y 2 1 Archimedes' principle dA2 dA dA1 A body submerged (partially or completely) in a fluid is buoyed up with a force equal in magnitude to the weight of the fluid displaced by the body

  12. Ideal fluid • nonviscous - there is no internal friction; • flows steadily - at any point, the velocity of the fluid does not depend on time; • incompressible - its density does not depend on pressure; • irrotational - does not produce vortices When the rate of flow is small (laminar flow), many fluids can be approximated by the ideal fluid.

  13. For in ideal fluid, the sum of the pressure, the kinetic energy per unit volume, and the potential energy per unit volume has the same value at all points along a streamline. Bernoulli's equation v2 y2 A2 dx2 v1 y1 A1 dx1 from the work-energy theorem:

  14. Thermal contact Two systems are in thermal (diathermic) contact, if they can exchange energy without performing macroscopic work. This form of energy transfer (random work) is called heat.

  15. Mechanisms of Heat Transfer 1. Thermal Conduction law of thermal conduction: A dx

  16. Mechanisms of Heat Transfer 1. Convection natural convection: resulting from differences in density forced convection: the substance is forced to move by a fan or a pump. The rate of heat transfer is directly related to the rate of flow of the substance. dQ = cTdm

  17. B E Mechanisms of Heat Transfer 1. Radiation Energy is transmitted in the form of electromagnetic radiation. Stefan’s Law  = 6  10-8 W/m2K A – area of the source surface e – emissivity of the substance T – temperature of the source

  18. Zeroth law of thermodynamics Thermal Equilibrium: If the systems in diathermic contact do not exchange energy (on the average), we say that they are in thermal equilibrium. If both systems, A and B, are in thermal equilibrium with a third system, C, then A and B are in thermal equilibrium with each other.

  19. h Temperature We say that two systems in thermal equilibrium have the same temperature. (Temperature is a macroscopic scalar quantity uniquely assigned to the state of the system.) Gas Thermometer T3 = 273.16 K is the temperature at which water remains in thermal equilibrium in three phases (solid, liquid, gas). The Celsius scale and, in the US, the Fahrenheit scale are often used. ;

  20. dl l D dD Thermal expansion For all substances, changing the temperature of a body while maintaining the same stress in the body causes a change in the size of the body. linear expansion: dl = ldl The proportionality coefficient (T) is called the linear thermal expansion coefficient. volume expansion: dV =VdV The proportionality coefficient (T) is called the volume thermal expansion coefficient.

More Related