P1 Flashcards
what are four energy stores
thermal
kinetic
gravitational potential
chemical
describe the energy transfers that occur as a ball falls to the ground
the ball transfers gravitational potential energy (GPE) into kinetic energy
give the equation for finding the energy in an objects kinetic energy store
kinetic energy= 1/2massspeed squared
if the energy is transferred to an objects kinetic energy store what happens to its speed
it speeds up
give the equation for finding the energy in an objects gravitational potential energy
GPE=massgravitational field strengthheight
what kind of energy store is energy transferred to when you compress a spring
elastic potential energy (EPE)
what is the definition of specific heat capacity of a material
energy required to increase temperature of material of a certain mass by 1°C
give the equation that relates energy transferred and specific heat capacity
change in thermal energy=massspecific heat capacitytemp change
state the conservation of energy principles
energy can be transferred usefully, stored or dissipated, but can never be created or destroyed
define power
the rate of energy transfer or the rate of doing work
give two equations to calculate power
power=energy/time
power=work done/time
what are the units of power
watts
how can you reduce unwanted energy transfers in a machine with moving, touching components.
using lubricant for example WD-40
does a thermal conductivity mean there is a high rate of energy transfers
yes
give four ways to prevent unwanted energy transfers in a home
cavity walls (gaps inside the wall reduce the amount of energy transfers by conduction through walls) loft insulation (reduce convection currents) double glazed windows (work the same way as cavity wall gaps) draught excluders (they are around doors and windows to reduce energy transferred by convection)
