Exam 4: Rotational kinetics N3L-Thermodynamics

Question 1

what is the rotational version of N2L?

Answer 1

M(A net) = I(A)α
- α = angular acceleration

Question 2

what does the rotational version of N2L tell us?

Answer 2

the sum of all torques (moments) about an axis A is equal to a moment of inertia about an axis A times the angular acceleration of the body
- A is fixed about a point/hinge/pin

Question 3

moment of inertia I(A)

Answer 3

positive quantity indicated how hard it is to get body rotating

Question 4

what does low I(A) tell us?

Answer 4

mass is close to axis of rotation which makes it easy to rotate

Question 5

what does high I(A) tell us?

Answer 5

mass far from axis of rotation

Question 6

what is the equation for moment of inertia at the center of a disk?

Answer 6

I = 1/2mR^2

Question 7

what is the equation for moment of inertia at the outside of a disk?

Answer 7

I = 3/2mR^2

Question 8

what side of the rectangle is the length? Width?

Answer 8

• the longer side => L for long
• the width is the shorter side

Question 9

what is the equation for moment of inertia for the center of a rectangle?

Answer 9

I = 1/12m(L^2 + W^2)

Question 10

what is the equation for moment of inertia for the long outside of a rectangle? (i.e located perpendicular to the length side)

Answer 10

I = 1/12mW^2 + 1/3mL^2

Question 11

what is the equation for moment of inertia for the short outside of a rectangle? (i.e perpendicular to the width)

Answer 11

I = 1/12mL^2 + 1/3mW^2

Question 12

what is the equation for moment of inertia for the corner of a rectangle?

Answer 12

I = 1/3m(L^2 + W^2)

Question 13

SI units of inertia (I)

Answer 13

kgm^2

Question 14

equation for torque (moment)?

Answer 14

M(A) = Fd

Question 15

what is the sign for CCW torque? CW?

Answer 15

+;-

Question 16

how do you get a total moment?

Answer 16

you add each individual moment

Question 17

what do you do if a force is not perpendicular to a line from the Axis of rotation?

Answer 17

you can move the location of the force anywhere along the line of action

Question 18

where does gravity act on a shape?

Answer 18

at the center

Question 19

what are the forces acting at the pin?

Answer 19

unknown forces called Rx and Ry that both equal 0

Question 20

what is newtons 2nd law with a rigid body?

Answer 20

F(net vector) = ma(vector COM)
- COM = center of mass

Question 21

Fluids

Answer 21

liquids and gases allow molecules to flow past each other

Question 22

phases for materials

Answer 22

1. solid
2. liquid
3. gas
   - go from 1-3 by increasing temp

Question 23

pressure

Answer 23

inside pressure and outside atmosphere push against one another
- push and pull on each side

Question 24

pressure calculation

Answer 24

force/area

Question 25

SI units of pressure

Answer 25

N/m^2 = Pa (pascal)

Question 26

how much is atmospheric pressure?

Answer 26

1.01 x 10^5 Pa at sea level - per 1 m^2

Question 27

fluid statics

Answer 27

fluid at rest - statics = at rest

Question 28

hydrostatic pressure

Answer 28

pressure in fluid at rest

Question 29

where on a column of fluid is pressure higher?

Answer 29

pressure at the lower point in a column is higher than the pressure at the top

Question 30

what is the equation between low and high pressure?

Answer 30

P(low) = P(high) + ρgh - ρ = rho

Question 31

ρ definition

Answer 31

Density of fluid - mass/volume - kg/m^3

Question 32

ρ(water)

Answer 32

1.0 x 10^3 Kg/m^3

Question 33

ρ(sea)

Answer 33

1.03 x 10^3 kg/m^3

Question 34

gauge pressure equation

Answer 34

P(G) = P(T) - P(ATM)

Question 35

what two tools do we use for the relationship between height and pressure for measuring pressure?

Answer 35

1. barometer 2. manometer

Question 36

Barometer equation

Answer 36

P(ATM) = ρgh - the top of the column has pressure = 0. This is added to right side

Question 37

manometer equation (true pressure)

Answer 37

P = P(ATM) + ρgh

Question 38

manometer equation (gauge pressure)

Answer 38

P(G) = ρgh

Question 39

Buoyancy

Answer 39

when an object is submerged in fluid at rest, fluid applies upward force on the object called the B force - for two objects with the same size and volume, the denser object will sink but the B force is =

Question 40

F(B) is equal to the weight of _____ ______ aka _____ principle

Answer 40

displaced fluid; archemedes'

Question 41

archimedes principle equation

Answer 41

F(B) = ρ(FL)gV(object) - volume of the object not velocity

Question 42

what fluid properties can be applied for dynamic fluids? (4)

Answer 42

1. steady 2. no viscous effects 3. incompressible 4. irrotational

Question 43

steady fluids

Answer 43

doesn't change over time

Question 44

incompressible fluids

Answer 44

density doesn't change - almost always for liquids and holds for gases when temperature and pressure doesn't change

Question 45

irrotational fluids

Answer 45

no whirlpools can be created - low turbulence which creates unpredictable effects

Question 46

what medically relevant cases are there for fluid dynamics?

Answer 46

1. blood flow through vessels 2. air flow through lung airway

Question 47

continuity

Answer 47

if the cross sectional area of a pipe changes, then speed of flow also changes to keep the volumetric flow rate constant

Question 48

does water flow fast through smaller or larger cross sectional areas?

Answer 48

smaller - slower through larger areas

Question 49

continuity equation

Answer 49

A1V1 = A2V2

Question 50

how can you calculate a circular cross section?

Answer 50

piR^2

Question 51

Bernoulli

Answer 51

fluid movement along a streamline for a single molecule

Question 52

Bernoulli equation

Answer 52

P(1) + 1/2ρV(1)^2 + Y(1)ρg = P(2) + 1/2ρV(2)^2 + Y(2)ρg

Question 53

what two things does the Bernoulli equation relate?

Answer 53

1. pressure to fluid speed 2. pressure and velocity to height

Question 54

1st law of thermodynamics equation

Answer 54

ΔE = Q + W - where ΔE = U + T + E(int)

Question 55

what is Q in thermodynamics?

Answer 55

energy added to a system by heat

Question 56

what is W in thermodynamics?

Answer 56

energy added to a system by work of non-conservative forces

Question 57

Work

Answer 57

changes in energy due to application of force

Question 58

Heat

Answer 58

changes in energy due to a temperature difference

Question 59

Internal energy

Answer 59

energy of the system that isn't represented by T or U

Question 60

what does higher temperature mean for internal energy? lower temperature?

Answer 60

greater internal energy; lower internal energy

Question 61

ideal gas law

Answer 61

pV = nRT - V is the ideal gas volume - n is the number of moles - T is the temperature in K - P is true pressure of the gas

Question 62

what is the universal gas constant?

Answer 62

8.314 J/Mol x K

Question 63

how do you find temperature in K?

Answer 63

C + 273

Question 64

Work of expansion is _____ if gas expands and ________ system energy

Answer 64

negative; removes

Question 65

Work of expansion is _____ if gas compresses and ________ system energy

Answer 65

positive; adds

Question 66

what is the relationship between internal energy and temperature of an ideal gas? (EQ)

Answer 66

ΔE(int) = mC(v)ΔT - m = mass of gas - Cv is 724 if temp is close to 100 deg C and 717 if temp is close to 21 deg C

Question 67

power cycle

Answer 67

uses heat transfer to do work with a cylinder and piston

Question 68

power cycle steps

Answer 68

1. gas pressure increases, temp increases, and volume of gas stays constant 2. no heat is transferred, volume increases, work is done on surroundings 3. Q leaves and gas volume decreases, temperature decreases

Question 69

refrigeration cycle steps

Answer 69

1. no heat transfer, external forces push piston down, temperature increases 2. no external force, heat leaves to high temperature, reservoir volume decreases 3. no heat transfer, volume increases, temperature decreases 4. heat transfers from cold temperature to gas in the chamber

Question 70

end card

Answer 70

:)