Engineering physics

lubricated, levitated with superconducting magnets, operating in vacuums

methods to reduce energy losses in flywheels

potters wheels, regenerative braking, storing excess electricity

uses of flywheels

efficient, dont degrade, short recharge and discharge time, ecofriendly

advantages of flywheels

heavy, can be unsafe, energy lost through fricion

disadvanages of flywheels

Q=dU+W

first law of thermodynamics`

dU=0

how does an isothermal change relate to the first law of thermodynamics

Q=0

how does an adiabatic change relate to the first law of thermodynamics

W=pdV

how does a thermobaric change relate to the first law of thermodynamics

steeper

how is the gradient of an adiabatic process different to an adiabatic process

induction, compression, expansion and exhaust

4 stages of petrol engine cycle

diesel doesn’t have a spark plug

difference between petrol and diesel engine cycles

same gas continuously used

assumption about gas in theoretical engine cycle

1.4

adiabatic constant of pure air

they are instantaneous

assumptions about pressure and temp changes within theoretical engine cycle

external

assumption about the heat source in a theoretical engine cycle

engine is frictionless

general assumption about engine in theoretical engine cycle

corners are rounded

difference between shape of theoretical and actual engine cycle

heating doesn’t take place at constant volume

difference between heating of theoretical and actual engine cycle

temperature rise not as high as heat source is internal and the gas air mixture never fully burns

difference between temperature of theoretical and actual engine cycle and why

area is smaller as work is done to overcome frictional forces

difference in size of theoretical and actual engine cycle and why

brake power

another name for output power

energy lost through moving parts

what is mechanical efficiency affected by

brake/indicated

ratio for mechanical efficiency

how well heat energy is transferred into work

what does thermal efficiency describe

indicated/input

ratio for thermal efficiency

brake/input

ratio for overall efficiency

heat engines must operate between a heat source and heat sink

second law of thermodynamics

assuming perfect conditions

how is maximum theoretical efficiency calculated

work is done to transfer heat energy from a cold space to a hot space

how do reversed heat engines work

a measure of how well work is converted into energy transfer

what is coefficient of performance

replace Qs in normal equation with temperature

how to calculate maximum theoretical coefficient of performance/efficiency for a reversed heat engine