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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 |