definations Flashcards
what is scalar quantity
-has magnitude (size)
what is vector quantity
-has magnitude (size) and direction
define velocity
speed with a given direction
define speed
distance covered in a given time
define acceleration
change in velocity per unit time
what do you call negative acceleration
deceleration
define displacement
Object/s overall change in position (how far from start to end)
define distance
how far an object moves (how much travelled)
define mass
amount of matter in an ogject
define gravitational field strength
gravitational force per unit mass
define weight
gravitational force acting on an object with mass
define density
amount of mass in a given volume
define analogue device
a measuring device that users have to read from a scale
define an digital device
a measuring device that displays the measurement instead of user reading it from a scale
define a pendulum
a weight suspended from a pivot so that it can swing freely
define freefall
motion under the force of gravity alone
define liner motion
motion where acceleration is not constant
define uniform motion
motion where acceleration is constant
define terminal velocity
steady speed of an object freely falling through a gas or liquid
Define force
a push , pull or a twist
define friction
force that opposes one surface moving or tying to move past another (opposes motion)
define static friction
force that keeps an object at rest
define dynamic friction
opposes sliding or rolling motion
what is resisting force
force opposing another force
What is resultant force
a single force that can replace all individual forces acting on the object, and have the same effect
define Newton’s 1 law
An object will remain stationery ( at rest) or move in a constant (uniform) speed in a straight line unless a net resultant force acts on it
define Newton’s 2 law
force = mass x acceleration
F = ma
define Newton’s 3 law
for every action, there is an equal and opposite force on it (forces act in pairs)
define Inertia
an objects resistance to change in speed and direction
define mass of body in inertia
a measure of inertia
Define balanced
forces in opposite directions that have the same magnitude
define human reaction time
time taken for a human reaction
define elastic object
an object that returns back to its original shape
Define limit of proportionality
-the point beyond which the extension of an elastic object is no longer directly proportional to the force applied to it
-(where it stop being proportional)
What is Hooke’s law
the extension of a spring is directly proportional to the force applied to it until it exceeds the limit of proportionality
define spring constant (k)
stiffness of spring
define spring extension (x)
extension of spring
define moment
turning force
define Equilibrium in a moment
the clockwise and anti-clockwise moments are equal (balanced) = resultant force and moment are 0
define pivot
turning point (need to touch the surface)
Define centre of gravity
point where the whole weight of an object seems to act
Define distance in moment
distance has to be perpendicular to pivot from the force
define a regular shape
has 1 or more lines of symmetry
define stability
how likely an object will fall when disturbed
define stable equilibrium
-object returns to its original equilibrium position
Define unstable equilibrium
-object does not return to its original equilibrium position
define Neutral equilibrium
-object remains in displaced position
what is pressure
force over area
define mechanical work done energy transfer
applied force
define electrical work done energy transfer
difference in charge causing electrical charges to move
define heat energy transfer
difference in temperature
define waves energy transfer
wave is transferred as radiation
define law of conservation of energy
energy cannot be created or destroyed
define law of conservation of mass
mass cannot be created or destroyed
define work done
transfer of energy by electrical or mechanical pathways
define power
how much energy / work done over time
define accurate
how close measurement is to the true/ accepted value
define precise
how close measurement of the same value are to each other
define reliability
how small the variations btw values are
Define nuclear fission
nuclei of atoms split apart
define renewable source of energy
energy that is made faster than used
define non-renewable source of energy
energy that is being used faster than it is made (unsustainable)
define melting
change of state of matter from solid to liquid
define boiling/ evaporation
change of state of matter from liquid to gas
define condensation
change of state of matter from gas to liquid
define freezing
change of state of matter from liquid to solid
define sublimation
change of state of matter from solid to gas
define depostion
change of state of matter from gas to solid
define heat
amount of thermal energy
define lattice
regular repeated arrangement of atoms
define temperature
average kinetic energy of particles
define Brownian’s motion
zig- zag motion of particles when suspended in fluid as a result of collision of particles in fluid.
what is pressure in container
force of particles colliding on the wall of the container
define expansion
particles gain thermal energy which is converted into kinetic energy to intermolecular forces and move apart
define absolute 0
-when particles have no kinetic energy = no movement
-measured in kelvin
define cold
absence of heat
what is 0K in C
0K = -273 C
define conduction
transfer of energy through collision of particles
define humidity
amount of water vapour in air
define insulators
poor conductors of heat eg. air, wood, plastic
define good conductors
conducts heat/ electricity easily
define convection
transfer of energy in fluids by creating a convection current where less dense hot particles rises and more dense colder particles sinks
define fluids
liquid or gas
define vacuum
no particles
define radiation
transfer of energy by a wave
define emission
release / give out
define transmission
traveling through a medium
define global warming
-average temperature of the earth increasing
define climate change
-long term changes of climate
define the greenhouse effect
the earth’s atmosphere traps heat
define longitudinal wave
wave which oscillations are parallel to direction of wave motion/ energy transfer
define transverse wave
wave which oscillations are perpendicular to direction of wave motion/ energy transfer
define compression
region with most pressure in longitudinal wave
define rarefaction
region with least pressure in longitudinal wave
define amplitude
max distance between the peak/ trough and position of equilibrium
define equilibrium
position where displacement is 0
define wave length
-distance btw 2 adjacent peak & trough/ compression & rarefaction
define a wave
-disturbance that transfers of energy without transferring matter away form source
define peak / crest
highest point of a transverse wave
define trough
lowest point of a transverse wave
define period
time taken for 1 wave length
define frequency
number of wave lengths per second
define oscillations
-max displacement of a wave
(vibrations)
what is λ
-lambda
-wave length
define wave speed
speed which wave travels in
define refraction
-change in direction of wave as they pass through different mediums
define reflection
-wave bounces off a plane surface
define electromagnetic waves
waves with vibrations btw electric and magnetic field
define diffraction
-bending at the ends of a wave as it passes through a narrow gap
define plane surface
2D flat surface
define echoes
reflected sound
define an oscilloscope
apparatus that converts longitudinal waves to transverse waves
define rule of incidence for reflection
angle of incidence = angle or reflection
define normal
perpendicular line from the surface
define wave front
-set of all locations in a medium where the wave is at the same place
imaginary surface that represent the points in a wave that vibrate tgt
-peaks of waves
-lines are equal
define ultrasound
sound with frequency higher than 20 000Hz
define infrasound
sound with frequency lower than 20Hz
define normal
perpendicular line from the surface
define non- luminous & eg
-reflect light
-moon, pen, book …
define luminous & eg
-produce light
-sun, lamp, torch
define monochromatic light
-light of a single λ & 1 colour
define critical angle
-when the refracted ray is perpendicular to normal
-varies with medium
define total internal reflection
-when incident angle is greater than critical angle, there is not refraction - only reflection
-in transparent medium
- has to be from more n to less n & incident angle is more than C
define virtual image
image that cannot be captured on a screen
-laterally inverted
-upright
-virtual
define real image
image than can be captured on a screen
define image
copy of a real object
define focal length
distance btw lens to principle focus
define principle focus
where all rays come tgt at a particular point
define principle axis
rays that are parallel to each other
