Flashcards in energy Deck (35):
whats the equation of density?
mass(kg) / volume (metres cubed)
whats the equation of volume?
what are the 4 main energy transfers?
mechanically (when a force moves through a distance), electrically(when a charge moves through a potential difference), heating (because of a temperature difference, by radiation (e.g. light, sound, microwaves, involving waves)
what is a veneer calliper and micrometer screw garages?
tools used to measure things smaller then 1mm
why do we need measurements in physics?
to give units to certain quantities such as time-seconds
how do you measure the time is takes for a pendulum to swing?
measure 10 swings then divide by 10
what is the independent variable of a swinging pendulum?
the length of the string cause the longer the string the longer it takes to swing
what is density measured in?
P(rho greek letter) (kg/m3)
what are the 8 energy stores?
nuclear(released through radioactive decay, fission or fusion), kinetic(in a moving object), magnetic (in 2 separate magnets that are attracting or repelling), gravitational(due to the position of an object in a gravitational field), thermal ( in a warm object), elastic(in a stretched or compressed spring), chemical(e.g. fuel or oxygen), electrostatic (in 2 separated electric charges that are attracting or repelling)
what are energy pathways?
certain ways which energy can be transported from one place to another
whats the law of conservation?
energy can not be created or destroyed only transferred
occurs when fluids (liquids and gases) are heated, the space between particles increases and the fluid expands. this decreases the density of the fluid and it rises. a convection (circulation) current is formed. this transfers energy from the hotter to cooler parts.
whats infrared raidation?
type of radiation that is produced and absorbed by every object
what are 2 ways of energy/ heat transferre ?
convection and infrared radiation
what are good absorbers of infrared radiation?
dark, matt surfaces are good at absorbing and emitting
what are bad absorbers of infrared radiation?
light, shiny surfaces are poor absorbed and emitters as they reflect infrared
what is the equation for efficiency ?
efficiency = useful energy output/ total energy input
whats percentage efficiency?
efficiency x 100 %
whats a sanky diagram?
a diagram used to show energy efficiency
what is wasted energy?
in most systems, not all of the energy supplied tot he system is transferred for the intended purpose. energy is lost as heat in most systems.
how do you make a snaky diagram?
the energy supplied is on the left written on the side of the box then the wasted energy always goes down and out put energy goes to the right and input doesn't have an arrow
whats the equation or work done?
work done ( joules (J)) = force(newtons) x distance (metres)
work done is the amount of energy transferred to an object is therefore measured in joules
whats force or newtons going to be?
10 cause the force of the earths gravity is 10
what should you always remember when working something out?
how do you calculate power ?
power(watts)= energy or work done (joules)/ divided by time (seconds )
what is the equation for kinetic energy?
Kinetic energy (joules)=1/2 mass(kg) x speed(metres per second) 2( squared) (V2)
2KE=M x V2
whats the equation for gravitational potential energy?
GPE (joules)= mass(kg)x gravitational field strength(newtons/ kg) x hight (metres)
what is the gravitational field strength usually?
10 because of the earths gravity
whats the equation for gravitational field strength ?
gravitational field strength= GPE/mxh
what energy transfer happens when starting a car?
chemical to kinetic by electricity
chemical as the petrol is a fuel and kinetic as the car is moving and and uses electricity to do so
how would we represent an athlete running in a snaky diagram?
you would put the amount of of chemical energy on the left in the input and the useful kinetic energy on the right arrow and the wasted thermal energy down in the below arrow.
transferred through mechanically
what is work done equal to?
the amount of work done is equal to the amount of energy transferred over a distance through a force
what is power?
the rate at which an object transfers energy (the amount of energy transferred per second). the more powerful an electrical appliance the faster it transfers energy
what is the relationship between work done and power?
you must calculate the amount of work done in order to calculate the amount of power as work done is energy measured in joules and in how long it is done in determines the amount out power in watts