A2 - Applied Flashcards
What is the definition of an isobaric system?
Pressure stays constant
How is an isobaric system created
Frictionless piston allowing pressure to be in equilibrium with surrounding.
What is characteristic of an isothermal system.
Constant temperature. Since I proportional to temperature, U=0
What key work is used for isothermal systems?
Slow
What is constant for an isothermal system? How is this derived from ideal gas law?
Pv constant. P=nkt/v. Since nkt constantly the, it looks like 1/x graph.
How do you test for an isothermal system.?
Check is pv is constantly the for all points on curve.
What is characteristic of isometric system?
Volume is constantly the.
What is constant in an isometric system.?
No work done.
What is the overall plot for an isomeric system.?
Horizontal line as pressure costsant
What is the shape of an isothermal Pv plot?
1/x plot.
What is the shape of an isometric pv plot?
Vertical line.
How do you calculate change in Intetnal energy of isomeric system?
Work=pv, hence area, U=Q-(pv)
How much work is done in an isometric system?
No work.
What is characteristic of an adiabatic system?
No heat transfer to he surroundings. Q=0
What is the difference between adiabatic and isothermal pv plots?
Adiabatic is steeper.
Which two words characterise adiabatic systems?
Insulated, rapid.
If the moment of I extra of roundabout is decreased, explain why the roundabout speeds up.
Angular momentum conserved, so the angular speed increased if I decreases.
How do you calculate the indicated power of FOUR STROKE engine from pV plot?
area enclosedcylinderscycles/min DIVIDED BY 2,
One in every two is a power stroke.
Why is diesel injected slightly before the top of the piston stroke
The fuel is compressed and starts to burn before top dead centre, maximising the pressure increase due to expanding fuel/air mixture, increasing power produced per stroke.
Why is the COP of heat pump greater than when working as refrigerator?
Work done + Qout=Qin for refrigerator, so Qin > Qout, therefore, looking at COP equations, we can see that COP for heat pump greater than refrig. for constant work done
