Physics Flashcards
name the 7 SI units
Time - seconds
temperature - kelvin
luminosity - candela
length - metres
amount of substance - moles
current - ampere
mass - kilogram
define precision
how consistent the results of repeated measurements are (how spread out they are)
define accuracy
how close the measured values are to the true value
define accuracy class
percentage of the inherent error of a measuring device compared to full scale deflection
define intrinsic error
error caused by faulty measuring equipment
define calibration
adjusting an instrument by comparing measurement from the instrument to a standard using a predefined interval
define uncertainty
range of values either side of the measurement where the true value is expected to be false
define error
difference between the true value and the obtained value
define correction
change required for the measured value to be the true value
define true value
value that would be obtained if the experiment was 100% accurate
define percentage error
relative error as a percentage
define scalar and give an example
magnitude
e.g. speed
define vector and give an example
both magnitude and direction
e.g. displacement
define resultant force
total amount of force acting on an object as well as the direction (vector)
define displacement
distance in a given direction
define speed
ratio of distance to time of a moving object
define velocity
change in displacement by the time taken for it to change
define acceleration
rate of change of velocity
define mass
property of a body which resists a change in velocity
define density
mass divided by volume
define weight
1N is the force required to give a mass of 1kg an acceleration of 1m/s
what is newton’s first law of motion
a body at rest will remain at rest, and a body in motion will remain in motion unless it is acted upon by an external force
what is newton’s second law of motion
the force acting on an object is equal to the mass of that object times its acceleration, F=ma
what is newton’s third law of motion
for every action, there is an equal and opposite reaction
define couple
a pair of equal parallel forces which produce rotational motion only
define equilibrium
no resultant force and no resultant torque in the system
define work
energy transferred to or from an object via the application of force along a displacement
define kinetic energy
a property of a moving object or particle and depends on both mass and motion
define gravitational potential energy
energy an object possesses because of its position within a gravitational field
define power
rate of doing work or converting energy from one form to another
define kilwatt-hour
a unit of energy equal to 3.6MJ
define efficiency
ratio of work output to input
define resultant force in crystals
the resultant force between two atoms in a crystal is the vector sum of an attractive force and a repulsive force
define elastic deformation
temporary change in form due to applied stress, reverting to original shape once stress is removed
define plastic deformation
permanent deformation in a solid object without fracture from a sustained force
define a slip
large displacement of one part of a crystal relative to another part along crystallographic planes and direction
define ductility
ability of a material to plastically deform without breaking
amount of stress applied before breaking
define brittleness
how much strain can be applied before breaking
define toughness
amount of energy stored before an object breaks
area under the curve on a stress-strain curve
define stiffness
ratio of force to extension
define hardness
ability to resist surface abrasion
define malleability
how deformed it can become before breaking
define strength
maximum amount of stress that can be applied before breaking
what is hooke’s law
the strain in a solid is proportional to the applied stress within the elastic limit of that solid
define current
rate of flow of charge
define resistance
opposition to the flow of electrons
define voltage
energy converted from electrical energy to another form when unit charge passes from one point to another
what is ohm’s law
current through a conductor is proportional to the potential difference across it, provided its temperature remains constant
define resistivity
relationship between the dimensions of a specimen of a material and its resistance
define capacitance
property of a conductor to store an electric charge
define time constant
time required for a capacitor to discharge and is resistance multiplied by capacitance
a capacitor takes about 5T to discharge
define inductance
a coil has a self-inductance of 1 henry if an e.m.f. of 1V is induced in the coil when the current through the coil changes at the rate of 1A per second
define non-destructive testing
used to collect information about a material in ways that do not alter it
define destructive testing
a test method conducted to find the exact point of failure of materials
define gauge pressure
pressure indicated on a gauge about that due to the atmosphere
define absolute pressure
gauge pressure + atmospheric pressure
define ideal fluid
one with assumed zero viscosity
define laminar flow
fluid moves along layers
define turbulent flow
particles move in very irregular patterns
define viscosity
fluid’s ability to resist shear forces
define specific heat capacity
energy required to raise the temperature of 1kg of a material by 1 degrees celcius
define sensible heat
heat energy absorbed or emitted during a change of temperature
define latent heat
heat energy absorbed or emitted during a change of state
define specific latent heat
energy required to change the state of a substance
what is the derived unit of charge
coulomb
what is the derived unit for power
Watt
what is the derived unit of energy
Joule
what is the derived unit of pressure
Pascals
what is the derived unit of force
Newton
define absolute zero
when an atom has the lowest internal temperature possible
define internal energy
total internal kinetic energy of motion of molecules
define kinematic viscosity
measure of a fluids internal resistance to flow under gravity
define dynamic viscosity
the ability of a material to resist flow and deform during mechanical oscillation
define Archimede’s principle
the up-thrust force of an immersed object is equal to the weight of the fluid it displaces
define electric field
region around a charged coil where a force would be exerted onto other charged particles or objects
define semiconductor
when a substance has a conductivity between an insulator and most metals
define conductor
an objects that allows the flow of charge
define yield point
when a solid object being stretched begins to undergo plastic deformation.
the amount of stress in an object before beginning plastic deformation
define endurance
objects ability to undergo repeated stress cycles
define watt
method of measuring the rate of energy transfer
