Powerpoint in physics part 1

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Powerpoint in physics part 1

  1. 1. PHYSICS 203L1 LECTURE First Semester 2012-2013 Group III - CE31FA1Technological Institute of the Philippines, Quezon City
  2. 2. FLUID MECHANICS• Fluid Statics – Study of fluids at rest in equilibrium situations.• Fluid Dynamics – Study of fluids in motion.
  3. 3. FLUIDS• Any substance that is free-flowing.• Include liquids and gases.• Non-rigid bodies.
  4. 4. DENSITY •M a s s p e r u n i t v o l u me •C o n s t a n t f o r e v e r y s u b s t a n c e •S I U N I T = k g /m 3 m V
  5. 5. • Wh i c h h a s a g r e a t e r De n s i t y ? Go l d B a r Go l d Ri n g
  6. 6. Specific Gravity (“Relative Density”) •Ratio of a material’s density to the density of water at 4 oC. ρwater @ 4 °C = 1000 kg/m3 = 1 g/cm3 Specific Gravity = Material Water
  7. 7. Fluid Pressure•Force per unit Area dF dP dA•If Pressure is constant throughout the area. F P A
  8. 8. HYDROSTATIC EQUILIBRIUM• Net force on the fluid is zero• i.e. Equal pressures on opposite directions.• i.e. Pressure difference gives rise to a net force.
  9. 9. Atmospheric Pressure (Patm)• Example of compressive fluid pressure.• Due to the Earth’s atmosphere.• Roughly constant near the surface of the earth. Patm 1atm 1.013 bar 14 .7 psi
  10. 10. PRESSURE DEPENDENCE• Pressure varies with depth.• Assumption: • Density is constant. • Acceleration due to gravity is constant. • Fluid is in equilibrium.
  11. 11. PRESSURE DEPENDENCE
  12. 12. Fy 0PA (P dP)A dW 0Recall : dW dmg;dm ρdV; dV AdyTherefore: dW ρdVg ρAgdySo :PA (P dP) ρgdy 0P P dP ρgdy 0dP ρgdydP ρgdy
  13. 13. PRESSURE DEPENDENCE In a fluid of constant density, take two points p, at y1, from the bottom and p2 at y2 from the bottom: dP ρgdy To Generalize: po y2 p = po + ρgh dP ρgdy p y1 p 2 p1 ρg(y2 y1 ) p 2 p1 ρgh p1 p 2 ρgh
  14. 14. Measured from below thesurface; upwardpositive.Measured from thesurface; downwardnegativeMeasured from thesurface; downward positive
  15. 15. The pressure p at a depth h is greater than thepressure po at the same level in the fluid.
  16. 16. • Gauge Pressure – Excess pressure above the atmospheric pressure. p gauge p p atm• Absolute Pressure – Actual Pressure
  17. 17. PASCAL’S PRINCIPLE• “Pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and the walls of the containing vessel. Hydraulic Lift F1 F2 p A2 A2
  18. 18. PRESSURE GAUGESOpen-tube Manometer •The U-shaped tube contains a liquid often water or mercury. •Left end is connected to a container where the pressure will be measured •Right end is open to the atmosphere. p ρgy patm ρgy2 p patm ρg(y2 y1 ) ρgh
  19. 19. PRESSURE GAUGES• Mercury Barometer • Of a long glass tube, closed at one end, that has to filled with mercury and then inverted in a dish of mercury. • Space above the mercury column contains mercury vapor (pressure is very small). • The mercury barometer reads the atmospheric pressure directly from the height of the mercury column
  20. 20. Ans. 1.9×104 N
  21. 21. Ans. 1.05×105 Pa
  22. 22. Ans. (a). 7.322×10−3 kg (b). VAu = 3.79×10−7 m3 , VCu = 7.46×10−8 m3 (c). 1.76×104kg/m3
  23. 23. Thank You Very Much!!!

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