Efficiency Flashcards
1
Q
What is a closed system?
A
A system that cannot transfer energy to its surroundings
2
Q
What is dissipation?
A
Wasted energy that cannot be recovered e.g heat loss
3
Q
What is a sankey diagram?
A
Diagram showing efficiency of energy transfers in a system
4
Q
What is efficiency?
A
- Percentage of energy supplied to a device that is useful
2. efficiency = useful energy/total energy x 100
5
Q
How can we increase efficiency?
A
- Lubrication
2. Thermal insulation
6
Q
How does lubrication reduce unwanted energy transfers?
A
Reduces work done by friction and t.f decreases energy dissipated
7
Q
How does thermal insulation reduce unwanted energy transfers?
A
Material that slows rate of energy transfers between two objects of diff temps
8
Q
How can we decrease the rate a house cools down by?
A
- Thicker walls
2. Walls made of materials w low thermal conductivity
