liquids, heat, soundwaves, light Flashcards
Force / Area
Pressure
force divided by area over which force is exerted
Pressure
density x depth
Liquid pressure
pressure and liquid exerts depends on (2):
- Depth
2. Density of liquid
Liquids are practically _______.
incompressible.
except for small changes produced by temperature, density of a particular liquid is practically the same at all depths
____ is the key to increased pressure.
depth
When liquid presses against a surface, there is a net force that is ______ to the surface.
Perpendicular
Loss of weight experienced by objects submerged in a liquid
buoyancy
when submerged, water exerts an upward force on the object that is exactly opposite to the direction of gravity’s pull
buoyant force
a completely submerged object always displaces a volume of liquid equal to its own volume
buoyancy
An immersed object is buoyed up by a force equal to the weight of the fluid it displaces
Archimedes’ Principle
The ____ determines the buoyant force
volume
whether an object will sink or float depends on how the buoyant force compares with the object’s ____.
weight
A floating object displaces a weight of fluid equal to its own weight
Principle of Flotation
A denser fluid exerts a greater _____ ____ than a less dense fluid.
buoyant force
A change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid.
Pascal’s Principle
Contractive tendency of the surface of liquids is called
surface tension
the rise of liquid in a fine, hollow tube or in a narrow space
capillarity
attraction between unlike substances
adhesion
attraction between like substances
cohesion
the property of fluid to resist motion
viscosity
quantity that indicates how warm or cold an object is with respect to some standard
temperature
____ is proportional to the average “translational” kinetic energy of molecular motion.
temperature
The energy transferred from one object to another because of a temperature difference between objects
heat
energy in transit
heat
grand total of all energies inside a substance
internal energy
Heat always flows from ___ to ___.
hot to cold
heat is measured in ____and/or ____.
joules and/or calories
the amount of heat required to change the temperature of 1 gram of water by 1 Celsius degree
Calorie
In reality, the heat unit to label food is actually the ____.
kiloCalorie (1000 calories)
how well a solid object conducts heat depends on the bonding within its atomic or molecular structure
conduction
Most ___ and ___ are poor conductors of heat.
liquids and gases
heat transfer due to the actual motion of fluid/gas
convection
transfer of energy by means of electromagnetic waves (a form of radiant energy)
radiation
List the order of wavelengths from longest to shortest.
- Radio waves
- Microwaves
- Infrared radiation
- Visible light
- UV radiation
- Xrays
- Gamma rays
the rate of vibration of the wave
frequency
infrared radiation is often called:
heat radiation
The to and fro vibratory motion (oscillatory motion) of a swinging pendulum in a small arc.
Simple harmonic motion
Pictorial representation of a wave.
Sine curve
distance from the midpoint to the crest (or trough) of a wave
amplitude
Distance from the top of one crest to the top of the next one
Wavelength
How frequently a vibration occurs; number of to and for vibrations it makes in a given time
frequency
unit of frequency
hertz
time for one complete vibration
period
wavelength / period
wave speed
waves produced when the motion of the medium is transverse (or at a right angle) to the direction the wave travels)
transverse waves
motion along the direction of the wave rather than at right angles to it
Longitudinal waves
when more than one wave occupies the same space at the same time
interference
when the crests of 2 or more waves overlap, and their individual effects add together to produce a wave of increased amplitude
contructive interference
when the crest of one wave overlaps with the trough of another, their individual effects are reduced
destructive interference
where parts of the object, called the nodes, are stationary
standing waves
regions of minimal zero displacement, with minimal or zero energy
nodes
regions of maximum displacement and maximum energy
antinodes
our subjective impression about the frequency of sound
pitch
non-periodic sound
pulse
condensed region of medium through which a longitudinal wave travels
compression
reduced pressure of the medium through which a longitudinal wave travels
Rarefaction
It is not the medium that travels across the room but the energy-carrying ____.
pulse
ability of a material that has changed shape in response to an applied force to resume its initial shape once the distorting force is removed
elasticity
____ and ___ ___ are generally excellent conductors of sound
Liquids and crystalline solids
speed of sound in air depends on (3):
wind conditions, temperature, and humidity
reflection of sound
echo
sound energy not carried by the reflected sound wave
transmitted wave
multiple reflections
reverberations
study of sound properties
acoustics
when sound waves bend when parts of the wave fronts travel at different speeds
refraction
sound travels _____ at higher altitudes and bends away from the ground.
slower
setting up of vibrations in an object by a vibrating force
forced vibration
frequency at which an elastic object naturally tends to vibrate if it is disturbed and the disturbing force is removed
natural frequency
when the frequency of forced vibrations on an object matches the object’s natural frequency and a dramatic increase in amplitude occurs
resonance
Waves arrive in phase and interfere _____ when the path lengths from the speakers are the same.
constructively
Waves arrive our of phase and interfere _____ when the path lengths differ by half a wavelength
destructively
_______ occur when sound waves reflect off walls and interfere with non-reflected waves to produce zones of low amplitude
Dead spots
periodic variation in the loudness of sound
beats
______ are due to interference. The sound that reached our ears throbs between maximum and minimum loudness.
beats
waves made from vibrating electric and magnetic fields that regenerate each other.
electromagnetic waves
classification of electromagnetic waves according to frequency
electromagnetic spectrum
glass and water allow light to pass through in straight lines. They are _____.
transparent
light travels at different average speeds through different materials
transparent materials
light is absorbed without remitting it
Opaque
when an electron is raised to a higher energy level, the atom has been ____
excited
excitation is temporary and returns to its lower energy state while emitting radiant energy
de-excitation
pulse of electromagnetic radiation caused by electrons dropping from higher to lower energy levels in an excited atom
photon
distribution of wavelengths in the light from a luminous source
Emission spectrum
light that is produced as a result of high temperature
Incandescence
property of certain substances to absorb radiation of one frequency and to re-emit radiation of lower frequency
Fluorescence
a type of light emission that is the same as fluorescence except for a delay between excitation and de-excitation, which provides an afterglow
Phosphorescence
Laser stands for:
Light Amplification by Stimulated Emission of Radiation
devices that produce a beam of coherent light. Beam of photons of the same frequency, phase, and direction
lasers
