energy Flashcards
what are the energy stores?
- thermal
- kinetic
- gravitational potential
- elastic potential
- chemical
- magnetic
- electrostatic
- nuclear
how is energy transferred?
- mechanically
- electrically
- heating
- radiation
what is work done?
energy transfer
what is the equation for kinetic energy?
kinetic energy = 1/2mv^2
what is the equation for gravitation potential energy?
GPE = m x gravitational field strength (N/kg) x h
what is the equation for elastic potential energy ?
EPE = 1/2 x spring constant x extenstion^2
what is specific heat capacity ?
-how hard it is to heat something up
the amount of energy needed to raise the temperature of 1kg of a substance by 1 degree
what is the equation for change in thermal energy?
change in thermal energy= m x specific heat capacity (j/kg) x temperature change
how do you investigate specific heat capacities?
- block of material with 2 holes, one for heater and one for thermometer
- measure mass of block
- insulate to reduce energy transfer
- measure initial temperature
- set power supply to 10 V and start stopwatch
- note temperature every minute (current SHOULD NOT change )
- 10 reading then turn of power supply
- use equation to find specific heat capacity
what is the equation for power?
power = energy transfer / time OR power = work done / time OR power = I^2 x R
what is the conservation of energy principle ?
energy CAN be transferred but can NEVER be created or destroyed
what does dissipated energy mean ?
wasted energy
what is power measured in ?
WATTS
what does one watt equal =
1 joule of energy transferred per second
what is conduction?
conduction = is the process where vibrating particles transfer to neighbouring particles
what energy store is heating?
THERMAL STORE
what is thermal conductivity?
a measure of how quickly energy is transferred through a material . High thermal conductivity means there is quick transfer of energy between particles .
what is convection?
convection is where energetic particles move AWAY from HOTTER TO COOLER
- only in LIQUIDS and GASSES
what happens when you heat a gas or liquid?
as particles can move, the space between the particles increase, causes density to decrease
how can a house be insulated ?
- thicker/ cavity walls
- thermal insulation
- loft insulation eg. fibreglass wool
- double glazed windows
how can you investigate the effectiveness of insulators ?
- boil water in a kettle in a sealable container and measure mass
- measure initial temperature
- seal container and wait 5 minutes
- remove lid and measure final temperature
- repeat with a different material wrapped around the container
what is the equation for efficiency?
useful output / total input
what is one of the only devices that can be 100% efficient?
an electric heater
how is energy wasted ?
HEAT
SOUND
