Mechanics II : Pressure, Oscillations, Waves. Flashcards
Definition of Pressure:
Pressure (p) is the force (F) applied perpendicular to a surface area (A).
SI Unit of Pressure:
SI Unit of Pressure: Pascal (Pa).
1 Pa = 1 N/m^2
Other commonly used units of pressure:
add the conversion values
1 mmHg = 133 Pa
1 bar = 105 Pa
What is the formula for Pressure?
π=πΉ/π΄
________ is a physical quantity with important application in physics, physiology and medical procedures. E.g. blood _______ cuff measurement
Pressure is a physical quantity with important application in physics, physiology and medical procedures. E.g. blood pressure cuff measurement
Definition of Density (π):
Density (π): The mass (m) of a homogenous body divided by its volume (V)
Formula for Density:
π=π/π
SI Unit for Density:
Density SI unit: kg/m3
The density of materials depend on their temperature and ________.
The density of materials depend on their temperature and pressure.
Definition of Hydrostatic pressure:
Hydrostatic pressure: Pressure in gases and liquids due to gravity.
Formula for Hydrostatic pressure:
p= Οβgβh
g is gravity constant (9.81m/s2 - precisely) and h is height (m).
Atmospheric (barometric) pressure - It ________ exponentially with elevation.
Atmospheric (barometric) pressure - It decreases exponentially with elevation.
The standard atmospheric pressure is ___ kPa= 1 atm
The standard atmospheric pressure is 101 kPa = 1 atm
The atmospheric pressure changes with _________
The atmospheric pressure changes with temperature
In a mixture of gases, each gas in the mixture will exert a pressure, this is called the _____ _______
In a mixture of gases, each gas in the mixture will exert a pressure, this is called the partial pressure
Formula for Partial Pressure:
ππππ‘πππ ππππ π π’ππ=πππ πππ’π‘π ππππ π π’ππ βπππππ‘πππ ππ πππ
Oxygen (21%) as an example for Partial pressure at sea level:
Partial pressure of O2 at sea level (PO2) = 1atm21%O2(of air) = 101kPa0.21 = 21.2kPa
The total pressure in the gas mixture is the ___ of all partial pressures
The total pressure in the gas mixture is the sum of all partial pressures
What is an Oscillation?
The periodic motion around an equilibrium point.
Sound in form of speech is created due to _______ of the vocal cords and hearing due to _________ of auditory ossicles.
Sound in form of speech is created due to oscillation of the vocal cords and hearing due to oscillation of auditory ossicles.
Definition of Harmonic oscillation:
Harmonic oscillation: Restoring force is working on a system displaced out of equilibrium.
For Harmonic Oscillation - The displacement is given as sine function of time, What is the formula?
π¦=π΄βsinβ‘(ππ‘+π0)
π - angular frequency,
π0 - initial phase
A - amplitude
What is the Point of equilibrium (In Oscillations) ?
Point of equilibrium: The point the system oscillates around
What is the Displacement (In Oscillations) ?
Displacement: The movement of the oscillating object away from the equilibrium point.
What is the Amplitude (A- In oscillations)?: Maximal displacement
Amplitude (A): Maximal displacement
What is the Period (T)?
Period (T): Duration of one cycle (s).
What is Frequency (f)? Unit?
Frequency (f): Number of cycles per unit time (1/s = Hz)
What is the formula for Frequency?
π=1/π
1/s = Hz
What is Angular frequency (π)?
Angular frequency (π) : 2π times frequency (1/s)
What is the Angular frequency (π) Formula
π=2πβπ
A physical system undergoing oscillations, is called an _______
A physical system undergoing oscillations, is called an oscillator
What is Hookeβs Law?
πΉ=βπ*π₯
πΉ - Elastic Force of a Spring
π - Spring Constant (Hookeβs)
x - Displacement
Define Simple Harmonic Oscillation, give an example as well
No energy loss during the motion
Classical example: Mass on a spring oscillator (Hookeβs Law)
What is Natural frequency (also called Eigenfrequency) ?
Natural frequency (also called Eigenfrequency) is the frequency of free oscillation (spontaneous oscillation without any external stimuli).
What is the formula for calculation of Eigenfrequency?
π0=1/2π β(π/π)
Definition of Damped oscillation:
Damped oscillation: Oscillations with energy loss as the time progress. Amplitude decreases with time.
Define Driven oscillation:
Driven oscillation: An external force is driving the oscillation.
What is Resonance?
Resonance: Vibration of a driven force together with a system
What is the Resonance curve?
Resonance curve: Represent the oscillation amplitude as a function of the driving frequency.
Resonance curve -The magnitude of resonance depends on _______ of the system
Resonance curve -The magnitude of resonance depends on damping of the system
Resonance curve - In a driven system, the resonance frequency goes towards the ___________
Resonance curve - In a driven system, the resonance frequency goes towards the eigenfrequency
What is a Wave?
A wave is a propagating oscillation
What types of waves are there? (based on origin, with examples)
1) Mechanical Waves (e.g. sound waves)
2) Electromagnetic wave (e.g. visible light, UV light)
What types of waves are there? (direction of oscillation and propagation)
1) Transverse Wave : The direction of oscillation is perpendicular to the direction of propagation.
2) Longitudinal Wave : The direction of oscillation is parallel to the direction of propagation
What is a Wavelength (π)? Unit?
Wavelength (π): The distance between two points of a wave with the same phase [m]
What is a Wave front?
Wave front: Surface containing points of waves in identical phases
Propagation of a wave: What is C?
C is the speed of light
Which is constnat?
Propagation of a wave: What is the releeationship between C, the Wavelength and the frequency of the Wave?
π= π/π=πβ1/π=ππ
from v=x/t
What is the Huygens-Fresnel principle?
Huygens-Fresnel principle: Concept of wave propagation. Every point of a wave-front is a source of a further wave.
What is a Spherical Wave?
The waves originate from a common point, but propagate in every direction.
What is a Plane wave?
Plane wave: The wave front form parallel planes to each other, but perpendicular to the direction of propagation.
Definition of Diffraction:
Diffraction: Occur when many sources of waves are present.
Definition of Interference:
Interference: Occur when 2 waves originating from different sources emerges and converge
Interference - Based on Principle of _________: The resulting wave is the sum of each individual wave function
Interference - Based on Principle of Superposition: The resulting wave is the sum of each individual wave function
Superposition means for the resulting wave that:
π ππ π’ππ‘πππ π€ππ£π=π€ππ£π1+π€ππ£π2
What types of Interference are there?
Can be constructive or destructive
Definition of Polarization:
Oscillation (i.e Light) is oriented in a preferred direction by a polarizer.
Only transverse waves can be polarized
Reflection Definition:
Reflection: The incident ray or part of it is returned at the interface between different media.
Types of Reflection:
1) Specular Reflection
2) Diffuse Reflection
Formula for law of reflection:
Formula for law of reflection:
πΌ=π½
πΌ - Incident Angle
π½ - Reflected Angle
Definition of Refraction:
Refraction: Change of direction when an incidence wave propagates from one medium into another.
What is Snellβs Law?
Snellβs Law: Describes the relationship between the angle of the incidence (π1) and refractory wave (π2) when passing from one medium (π1) to another medium (π2).
Formula for Snellβs Law:
π1 *sinβ‘(π1)=π2 *sinβ‘(π2)
π ππ(π1)/π ππ(π2 )=π1/π2
