Unit 1 Energy stores & systems Flashcards
what is a system
An object or group of objects
when are there changes in the way energy is stored?
when a system changes
system changes in an object moving upwards
kinetic energy equation
1/2 x mass x (speed)2
elastic potential energy equation
1/2 x spring constant x (extension)2
what is the specific heat capacity of a substance?
The amount of energy required to raise the temperature of one kilogram of the substance by one degree celcius.
Power
rate at which energy is transferred or the rate at which work is done
work done
force x distance
change in thermal energy equation
mass x specific heat capacity x temperature change
how many watts is an energy transfer of 1 joule per second equal to?
a power of 1 watt
power equations
power= work done/ time
OR
power= energy transferred/time
Law of conservation of energy
Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed.
describe what happens with energy transfers in a closed system.
no net change to total energy
ways of reducing unwanted energy transfers
- lubrication
-use of thermal insulation
relationship between thermal conductivity of a material and the rate of energy transfer
the higher the thermal conductivity of a material, the higher the rate of energy transfer by conduction across the material.
