ME 2334 Thermodynamics Exam 1 Questions and Answers
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ME 2334 Thermodynamics
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ME 2334 Thermodynamics
ME 2334 Thermodynamics Exam 1
thermodynamics - Answer- the science of energy
conservation of energy principle - Answer- energy cannot be created nor destroyed but it can be transformed from one form to another if total energy remains constant.
first law of thermodynamics - Answer- energy c...
ME 2334 Thermodynamics Exam 1
thermodynamics - Answer- the science of energy
conservation of energy principle - Answer- energy cannot be created nor destroyed
but it can be transformed from one form to another if total energy remains constant.
first law of thermodynamics - Answer- energy conservation principle
second law of thermodynamics - Answer- energy is described by quantity and quality
processes occur in the direction of decreasing quality of energy
classical thermodynamics - Answer- macroscopic approach to studying
thermodynamics that does not require knowledge of the behavior of the molecules
ex) examining air's properties (density, P, and T)
molecular/statistical thermodynamics - Answer- microscopic approach to studying
thermodynamics
focuses on the behavior of molecules
ex) examining the molecular makeup of air
conversion from foot to meter - Answer- 1 ft = 0.3048 m
conversion from lbm to kg - Answer- 1 lbm = 0.4536 kg
units of force - Answer- 1 N → force required to accelerate a mass of 1 kg at a rate
of 1 m/s²
1 lbf = 4.448 N
units of work/energy - Answer- 1 J → the work done by a force of 1 N actioning of a
distance of 1 m (1 N* 1 m)
1 calorie (English) = 4.1868 J
1 Btu = 1055 J
power (W) - Answer- 1 W → 1 J of work done in 1 s
how fast or slow energy is produced/work being done
as power ↑, work ↑ or time↓
1 hp = 746 W
system - Answer- a system is defined as a quantity of matter or a region in space
chosen for a study. it is contained by a boundary
surroundings - Answer- the mass/region outside of the system/boundary
boundary - Answer- the surface that separates the system from the surroundings
zero thickness, mass, and volume
can be moving (balloon), or flexible, or fixed
, closed system with a fixed boundary - Answer- there is no mass exchange, but
energy change can still occur. volume is fixed, energy is not necessarily fixed. the
mass is controlled
closed system with a moving boundary - Answer- there is no mass exchange, but
energy change can still occur. volume is changing, energy is not necessarily fixed.
the mass is controlled
open system - Answer- can have both mass and energy exchange. the volume is
controlled.
property - Answer- any characteristic of a system
ex) pressure, temperature, and density
extensive property - Answer- dependent on the mass of the system
ex) mass, volume, and energy
can be converted into an intensive property by dividing by mass. these properties are
known as specific properties. changes when a system is divided into 2
intensive property - Answer- independent of the mass of a system
ex) temperature, pressure, and density.
does not change when a system is divided into 2
continuum - Answer- a continuum disregards the atomic nature of a substance and
views it as a continuous, homogeneous matter with no holes or gaps. matter is
continuously distributed within the system. any point can be assigned a property.
(the molecular view has gaps between molecules so masses/values can not be
assigned to certain points where there are gaps)
continuum assumption - Answer- valid if the characteristic dimension (length) of a
system is much greater than the mean free path of molecules. any length you can
associate with a system is a characteristic length.
mean free path - Answer- the distance a molecule travels before collision with
another molecule, approximately 10^-8 m.
density - Answer- density=mass/volume
ρ=m/V [kg/m³]
a function of T and P for a gas
a function of T for a liquid (T has a weak effect)
specific volume - Answer- specific volume=1/density
v(nu)=1/ρ [m³/kg]
specific gravity - Answer- SG = density of a substance/density of water
[dimensionless]
the density of a substance relative to that of water
SG > 1 → heavier than water, will sink when placed in water
SG < 1 → lighter than water, will float
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