Finals Flashcards
Examples of fluid mechanics
Industrial applications
Piping plumbing system
Natural flows and weather
Power plants
Boats
Human Body
Aircraft and spacecraft
Intermolecular bonds are strongest in
solids and weakest in gases. T/F
True
In liquid groups of molecules can move relative to
each other, but the volume remains relatively constant because of the strong cohesive forces between the
molecules. As a result, a liquid takes the shape of the container it is in. T/F
True
A gas expands until it encounters the walls of the container and fills the entire available space. This is because the gas molecules are widely spaced, and the cohesive forces between them are very small. Unlike
liquids, a gas in an open container cannot form a free surface. T/F
True
ratio of an object’s density to the density of
water at 4.0 degree celsius (1000 kg/m3 )
Specific gravity (s.g) or relative density
defined as the normal force F per unit area A over which the force is applied.
Pressure
-pressure of the earth’s atmosphere.
-varies with weather changes and with elevation
Atmospheric pressure
At sea level, the normal atmospheric
pressure is?
1 atmosphere (atm) is given by
1.013x105 Pa
Pressure is measured using two
references:
- Atmospheric pressure- gauge pressure
- Absolute vacuum/zero pressure-Absolute pressure
difference between unknown pressure and atmospheric pressure
Gauge Pressure
true pressure; includes the atmospheric pressure
Absolute pressure
Pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and the walls of the containing vessel.
-Pressure applied on one point of liquid transmits equally in all direction
Pascal’s Law
When a body i s completely or partially immersed in a fluid, the fluid exerts an upward force, called the buoyant force, on the body equal to the weight of the fluid displaced by the body.
Archimedes’ principle
Why do buoyant force occurs?
because the upward pressure on the bottom
surface of a submerged object is greater than the downward pressure on top of its surface.
is a curved tangent at each point to
the velocity
Stream Line
is the medium of the fluid
Flow tube
occurs when no change in pattern is observed and the total mass in the tube is constant
Steady flow
The principle states that “the pressure of a fluid [liquid or gas] decreases as the speed of the fluid increases.”
-Within the same fluid (air in the example of aircraft moving through air), high-speed flow is associated with low pressure, and low-speed flow is associated with high pressure.
Bernoulli’s Principle
states that the work done on a unit volume of fluid by the surrounding fluid is
equal to the sum of the changes in kinetic and potential energies per unit
volume that occur during the flow
Bernoulli’s Principle
Application of Bernoulli’s principle
Wings and sails
Venturi mask
Fast-moving train
Roofs blown away by heavy winds
what law that states if a system C is initially in thermal equilibrium with both systems A and B, then A and B are also in thermal equilibrium with each other
Zeroth Law of Thermodynamics
-The Measure of the average kinetic energy of all the particles in the object.
Temperature
Change in physical dimensions when subjected to change in temperature
● Most materials expand when heated
Thermal Expansion
If a metal sheet with a hole in the middle is subjected to heat, what will happen to the hole?
When a metal sheet with a hole in the middle is heated, the hole will get larger.
-As the metal is heated, it expands in all directions due to thermal expansion.
-The expansion occurs uniformly, so every part of the metal, including the edges around the hole, moves outward.
-This causes the hole to increase in size, not shrink.
0°C ≤ T ≤ 4°C:
water decreases in volume with increasing temperature
T> 4°C:
water increases in volume with increasing
temperature
is defined as the transfer of energy across the boundary of a system due to a temperature difference between the system
and its surroundings.
Heat
energy transfer that takes place solely because of a temperature difference
Heat flow/heat transfer
the temperature rise is __________ to the amount of work done
proportional
Heat is measured by the units of?
Calorie and joule (J)
the amount of energy needed to raise the temperature of that by 1°C
Heat Capacity
The value of the specific heat of a gas depends on whether the ___________or __________________is held constant
Pressure or volume
-is the science of measuring changes in parameters
-chemical reactions, physical changes, and phase transition
-for the purpose of deriving the heat associated with those changes
Calorimetry
do not need any medium for propagation
Electromagnetic waves
do not have electromagnetic properties
Matter waves
Types of Waves
-Electromagnetic waves
-Matter waves
-Mechanical Waves
Disturbance of a system from equilibrium that propagates from one region of the system to another
Wave
require a medium in order to propagate
mechanical waves
Kinds of mechanical waves
-Transverse wave
-Longitudinal Wave
Particles in the medium vibrate perpendicular to the direction of the propagation of the wave
Transverse Wave
Particles in the medium vibrate parallel to the direction of the wave
Longitudinal wave
is the measure of the displacement of the wave from its rest position
Amplitude
distance between two crests or
two troughs or between
Wavelength
time elapsed between two successive crests passing the same point in space
Period
number of cycles that pass a given point per unit time
Frequency (f)
angular displacement per unit time
Angular frequency (ω)
relationship between wavelength and frequency
inversely proportional
is dependent on the properties of the medium through which it travels. This means that if the properties of the medium change, the speed of the wave will also change.
Wave speed
-is a periodic wave whose waveform (shape) is the trigonometric sine function.
-Periodic wave with simple harmonic motion
Sinusoidal wave
The reflection of a traveling pulse at the fixed end of a stretched string. The reflected pulse is________________, but its shape is otherwise unchanged
inverted
The resulting effect when two or more
waves overlap in the same region of space.
Wave Interference
Occurs when two waves of the same frequency and amplitude but traveling in opposite direction interfere
-does not appear to be moving in either direction
standing wave
The distance between adjacent antinodes is equal to
λ/2
The distance between adjacent nodes is equal to
Half of the wavelength or λ/2
The distance between a node and an adjacent antinode is
λ/4
sequence of frequencies in which each frequency is an integer of a fundamental
Harmonic series
any frequency greater than the fundamental frequency
Overtone
