Powerpoint in physics part 1
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This document summarizes a physics lecture on fluid mechanics. It discusses key topics like fluid statics, fluid dynamics, density, pressure, hydrostatic equilibrium, pressure dependence on depth, Pascal's principle, and pressure gauges. Measurement tools like manometers and mercury barometers are also covered. The lecture provides essential information about concepts and calculations in fluid mechanics.
Powerpoint in physics part 1
- 1. PHYSICS 203L1 LECTURE First Semester 2012-2013 Group III - CE31FA1 Technological Institute of the Philippines, Quezon City
- 2. FLUID MECHANICS • Fluid Statics – Study of fluids at rest in equilibrium situations. • Fluid Dynamics – Study of fluids in motion.
- 3. FLUIDS • Any substance that is free-flowing. • Include liquids and gases. • Non-rigid bodies.
- 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
- 6. • 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
- 7. 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
- 10. Fluid Pressure •Force per unit Area dF dP dA •If Pressure is constant throughout the area. F P A
- 11. 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.
- 12. 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
- 14. PRESSURE DEPENDENCE • Pressure varies with depth. • Assumption: • Density is constant. • Acceleration due to gravity is constant. • Fluid is in equilibrium.
- 16. Fy 0 PA (P dP)A dW 0 Recall : dW dmg;dm ρdV; dV Ady Therefore: dW ρdVg ρAgdy So : PA (P dP) ρgdy 0 P P dP ρgdy 0 dP ρgdy dP ρg dy
- 17. 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
- 18. Measured from below the surface; upward positive. Measured from the surface; downward negative Measured from the surface; downward positive
- 19. The pressure p at a depth h is greater than the pressure po at the same level in the fluid.
- 20. • Gauge Pressure – Excess pressure above the atmospheric pressure. p gauge p p atm • Absolute Pressure – Actual Pressure
- 21. 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
- 22. PRESSURE GAUGES Open-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
- 24. 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
- 25. Ans. 1.9×104 N
- 26. Ans. 1.05×105 Pa
- 27. 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
- 28. Thank You Very Much!!!