Energy Transfers Flashcards
1
Q
Two key points on energy transfer
A
- can be transferred usefully, stored or dissipated
- cannot be creates or destroyed
2
Q
What is a closed system
A
Total energy never changes, but it can be transferred from one store to another
3
Q
Example of a closed system
A
- electricity powered lift raises lift carriage:
- transfers electrical energy into gravitational potential energy
- some energy is dissipated into surroundings as heat and sound
- wasted energy is no longer available for useful transfers
4
Q
How does thermal conductivity affect rate of cooling
A
-depends on thickness and thermal conductivity
— SO thin walls with high thermal conductivity will conduct heat the quickest and the building will cool down rapidly
