Topic 1.8- 1.11 Flashcards
cconduction and convection- power- work done -efficiency
How is heat transferred through different states
Solid- Conduction
Liquid or Gas- Convection
Empty Space- Radiation
Define Conduction
Vibrating particles transfer energy to neighboring particles, happens mostly in solids as the particles are very close
What is Thermal Conductivity
An objects ability to transfer energy by conduction. Metals have high thermal conductivity
Explain convection
- particles are heated which increases their kinetic energy
- thy heated particles spread out coming less dense and rise
- cooler particles sink to the bottom
What is a convection current
a cycle where hot particles rise meaning cooler particles sink and then become heated so start to rise. the originally heated particles start to cool, condense and sink and the secondary heated particles take their place at the top
How do you reduce convection
stop the free flow of fluids
How is heat energy transferred in a vaccum
by radiation through infrared waves- hotter and object is the more radiation it emits
What are the two definitions of power
- the rate at which energy is transferred
- the rate at which work is done
What are the two equations for power
- Power (Watts, W) = Energy (Joules, J) / time (seconds, s)
P=E/t - Power (Watts, W) = Work done (Joules, J) / time (seconds, s)
P=W/t
What is the definition of work done
A force being used to move an object by a certain distance
What is useful energy/power output
energy transferred into the store we want it to be in
what is waste energy
energy transferred into a store that we dont want it to be in
define efficiency
the proportion of energy transferred into the useful energy output
What is the calculation for efficiency
Efficiency = useful energy output/ total energy input
