energy transfer Flashcards
(16 cards)
what is dissipated
spread out to the surroundings
state the law of energy conservation
energy cannot be created or destroyed
what happens to the energy in a closed system
energy never changes but can be transferred
state any changes in the total energy of a ball that is kicked, assuming there’s no external force
total energy of system remains the constant due to the conservation of energy
Describe the energy changes that occur in a filament light-bulb.
what are the useful and waste energy
electrical energy is transferred to heat and light energy
useful-light
waste-heat
how can the efficiency of a system be increased
reducing and recycling waste outputs
How can unwanted transfers be reduced
lubrication, tightening loose parts, thermal insulation
what is lubrication
reduces friction that produces heat
what does tightening loose parts prevent
prevents unwanted vibration
what key factors affect the rate of cooling of a building
thickness and thermal conductivity of the wall
a 20W light bulb transfers 15W usefully as light energy. What happens to the energy that is not transferred as light
released as heat and lost to the surroundings
Do double glazed windows have a higher or lower thermal conductivity than a single-glazed window
lower, less energy transfers through them
state 2 methods of reducing heat loss in a building
-double glazing
-wall insulation
how can the efficiency of a mechanical machine with moving parts be improved
lubricate any moving parts to reduce the friction
how can efficiency of a radiator be improved
installing metal foil sheets behind radiator to reflect heat back into room rather than being absorbed into the wall
how can efficiency of s boiling water in a pan be improved
placing a lid on the pan to reduce heat loss
