Physics Flashcards
measure of the total energy of a thermodynamic system
Enthalpy
if the energy is released during a reaction. Such a reaction is called ………and the delta H is negative
Exothermic reaction
If the energy could be consumed in a reaction. Such reactions are called ……and the delta H is positive here
Endothermic reaction
The ability to do work because of position is called
potential energy
The ability to do work because of motion is called
Kinetic energy
The SI unit for power is
Watt
Bourdon tube would typically be used to measure?
Gage pressure
A temperature of 0 K corresponds to
-273 °C
The SI units of relative density are
unitless
The SI units for specific weight are
KN/m3
The result when we have a force per unit area is
Pressure
A force through a distance is referred to as
work
The capability of doing work is referred to as
energy
The base SI units of density are
Kg/m3
The SI unit for work is
Joule
In terms of viscosity, a fluid that behaves in a linear fashion according to the shear stress/velocity gradient relationship would be considered to be a
Newtonian fluid
________ is a substance’s absolute viscosity over its density
Kinematic viscosity
Dynamic viscosity is a function of
Sheer stress over shear rate
Viscosity will typically decrease in liquids if
the temperature increases
Viscosity will typically increase in gases
if the temperature increases
Density will typically increase in all substances if
the pressure increases
Adiabatic process
no heat is absorved
Specific heat of water
4.183 KJ/Kg °C
Specific heat of ice
2.135 KJ/Kg °C
Latent heat of fusion of ice
335 KJ/Kg °C
Latent heat of vaporization of steam
2257 KJ/Kg °C
Applying energy results in direct temperature change in substance. No phase change
Sensible heat (kinetic energy)
Applying energy doesn’t result in Δt but goes towards changing the phase of the substance.
Latent Energy (hidden energy)
Melting or freezing ie. Ice
Latent Heat of fusion
Boiling, condensing ie Steam
Latent Heat of vaporization
Used to describe a point where a change of state in a substance takes place
Saturation
No liquid – Saturated
Dry Steam
dryness fraction (fraction that is vapor)
q
Saturated steam where temperature rises again
Superheat of steam
Changing ______ changes boiling point
pressure
Triple Point
The point at which solid, liquid, gas, coexist in equilibrium
Vapor
A gas not far removed from liquid state
Sublimation
Solid Phase passes directly to vapor
Enthalpy Increases with
increase of pressure
What happens to Latent heat with rise in pressure
Latent Heat goes down
Critical Temperature
The temperature at which gas cannot be liquefied regardless of pressure applied
Ideal Gas
Any gas that obeys ideal gas laws NOT vapours
volume occupied by one gram mole of gas
Molar volume of Gas
Ideal gas Law
PV=RT
The internal energy (U) and then enthalpy (H) of an ideal gas only depend on
temperature
Boyle’s law
If gas is under constant temperature then volume wil vary inversely with change in absolute pressure
PV/T
Charles Law
Gas under constant volume will have pressure vary dirrectly with temperature
PV/T
Gas expands contracts without energy
Adiabatic
Polytropic
No system truly ever doesn’t lose heat
Where the fluid moves slowly in layers in a pipe, without much mixing among the layers.
Laminar flow
Reynolds number < than or = to 2000
Laminar flow usually happens in small pipes and low flow velocity
Reynold’s Number > than or = to 4000
Turbulent flow
unpredictable, high flow rates
Typically occurs when the velocity is low or the fluid is very viscous.
Laminar flow
In between 2000 and 4000 (Reynolds number)
Critical Region Flow or Transitional flow- it is not possible to predict what type of flow exists.
Can be either laminar or turbulent difficult to pin down.
Reynold’s number is directly proportional to velocity and inversely proportional to
viscocity
Turbulent flow - friction factor
based on inside roughness of the pipe and reynolds number
the pipe friction loss increases linearly with the flow velocity, and it depends only on the viscosity of the liquid.
laminar flow
Centrifugal pump
(Kinetic) High flow rate low pressure rise
Dynamic suction head (Hs)
Static suction head minus the friction head
Static discharge head
vertical distance between the pump centerline and the free level of the fluid in the discharge tank
Dynamic discharge head
Static discharge head + friction head + velocity head
