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# EK Physics 5

### fluids and solids

Question | Answer |
---|---|

density | rho = m/v SI units of kg/m^3 all fluids/solids will have constant density on MCAT |

specific gravity | S.G. = density of substance / density of water |

density of water in kg/m^3 | 1000 |

density of water in g/cm^3 | 1 |

fluid pressure | pressure experienced by object submersed in fluid, resulting from impulse of molecular collision on the surface area of the object; measure of KE due to random velocities of molecules w/in fluid distributed over fluid volume |

pressure equals.. | P = F/A SI unit, Pascal |

pressure for fluid at rest | P = rho*g*y where y is the depth of the fluid |

in any fluid open to atmosphere, pressure equals | P = pgy + P atmosphere where Patmosphere = 101,000 Pa |

gauge pressure | measure of pressure compared to local atmospheric pressure |

Pascal's principle | pressure applied anywhere to an enclosed incompressible fluid will be distributed undiminished throughout the fluid |

hydraulic lift | simple machine that works via Pascal's principle where pushing up on piston 1 will push up piston 2 (pressure on incompressible fluid) |

buoyancy force | Fb = pfluid*V*g where V is the volume of the fluid displaced *doesn't change w/depth |

fraction submerged = | = density of floating object / density of the fluid |

ideal fluid | has no viscosity, is incompressible, lacks turbulence, and experiences irrotational flow, flow rate is constant |

continuity eqn | Q = Av where Q is the volume flow rate, A is the cross-sectional area of the pipe, and v is the velocity |

Bernoulli's eqn | P + pgh + 1/2pv^2 = constant |

velocity of fluid emptying in a tank | v = sqrt(2gh) |

fluid in pipe- as velocity increases, pressure... | decreases |

streamline | path followed by a hypothetical fluid particle; closer they are, the greater the velocity but they never intersect |

non-ideal fluids and pipe narrowing | will increase the velocity of the non-ideal fluid (so would ideal fluid) but drag must be taken into consideration - will not increase velocity as much as in ideal fluid |

fluid tends to flow from high pressure to low pressure - eqn? | change in pressure = Q*R where R is the resistance to flow |

surface tension | intensity of the intermolecular forces per unit length, responsible for formation of water droplets where intermolecular forces pull inward to minimize surface are |

surface tension is dependent on.. | temp of fluid (higher T, weaker ST) |

capillary action | balance btw the intermolecular forces of the fluid molecules (cohesive) and the forces btw fluid molecules and the tubing (adhesive) |

cohesive forces stronger in tube.. | (ST forces) fluid is pulled downward by ST and forms convex meniscus |

adhesive forces are stronger in tube .. | (forces btw fluid and tubing) fluid is pulled upward by ST and forms concave meniscus |

stress | force applied to object divided by the area over which the force is applied = F/A |

strain | fractional change in an object's shape = change in dimension/original dimension |

modulus of elasticity | stress/strain |

Young's modulus | (E) tensile stress modulus |

shear modulus | (G) shear stress modulus |

bulk modulus | (B) compression and expansion |

linear thermal expansion | change in length = length*alpha*change in T where alpha is constant unique to the particle substance |

volume thermal expansion | change in volume = volume * beta * change in T where beta is the constant unique to the particular substance |