Practical Exam Flashcards
Density def:
Property indicating how much substance is in unit of volume
Density formula:
p = m/V (mass, volume) kg/m^3
Density SI
Kg/m^3
Density depends on
Temperature, mass, crystalline form
If T goes up p goes down, exception for water
Density of heterogenous
p(r) = dm(r)/dV(r)
Relative density of liquid
p = p(liquid)/p(solution)
Measuring density of liquids (material)
- scale
- pipette
- pycnometer
- distilled water
- solution sample
Density of liquids procedure
- weigh empty pycnometer
- fill with water and weigh
- fill with sample and weigh
- find pycnometer volume
- calculate density
Density of solids material
- scale
- pycnometer
- solid
- distilled water
Density of solids procedure
- weight solid in air
- fill pycnometer with water znd weigh
- fill water pycnometer with solids and weigh
- calculate
What is measurement of density of solids by immersion technique based on
Archimeds law: a solid is lighter in water than in air
Buoyant force formula
Fb = mH2O x g
Density of solids by immersion material
- scale
- beaker
- water
- sample
Density of solids by immersion procedure
- weight sample in air
- weight sample immersed in water
- calculate
Order of magnitude
Approximating answer
Fluids definition
Substance that can flow, given by velocity of particles per time
Flaw rate through pipe
Quantity of fluid passing through cross section of pipe in unite time
Volumetric flow rate
Qv = delta V /delta t
SI = m^3/s
Mass flow rate
Qm = delta m / delta t
SI: kg/s
Relation btw mass flow rate and voluletric flow rate
Qm = p x Qv
Laminar or streamline flow
- liquid flows smooth
- parallel layers to direction of flow
- low energy consume
Turbulent flow
- molecular flow irregulzr
- generate currents
- high energy consumption for flow rate
Viscosity def
Resistance to flow
Viscosity determinced by
- internal frictions btw layers of fluid
- determined by size of molecules
- more temperature leads to lower viscosity
Motion of liquid newtonian law
F = nxAx(delta Vx / delta y)
Constant of proportionality n
- represents dynamic viscosity of liquid
- SI: (N x s)/m^2 = Pa x s
Newtonian fluids
If dynamic viscosity of fluid depends on velocity, liquids are non newtonian like blood
Flow rate through cylindrr formula
Qv = delta (p . pi . r^4)/(8.n.L)