Class 4

Question 1

Temperature is related to average _______ of molecules.

Answer 1

Kinetic energy

Question 2

Is temperature an intensive property? What does that mean?

Answer 2

Yes. Doesn’t depend upon the amount of material

Question 3

Is heat an intensive property?

Answer 3

No! It depends on the amount of material and is thus extrinsic.

Question 4

Does a material change temperature during phase change

Answer 4

No

Question 5

What is the Zeroth Law of Thermodynamics?

Answer 5

Defines temperature as a fundamental property of any substance. When two substances are in contact, heat transfers between them until they achieve the same temperature, i.e. thermal equilibrium.

Question 6

What are 3 modes of heat transfer?

Answer 6

1. Conduction
2. Convection
3. Radiation

Question 7

What is conduction?

Answer 7

Heat transfer through solids in direct contact.

Ability to conduct is material-dependent.

Question 8

What is convection?

Answer 8

Heat transfer through fluid circulation

Question 9

What is radiation?

Answer 9

Heat transfer by emission and absorption of electromagnetic energy

Question 10

What are the relative speeds of heating?

Answer 10

Conduction -> Convection -> Radiation

slowest fastest

Question 11

What is the equation for the first law of thermodynamics?

Answer 11

(delta)E = Q - W

Question 12

Work (W) is positive when what does the work?

Answer 12

The system. Work done ON the system will be negative

Question 13

When is Q positive/negative in thermodynamics?

Answer 13

Positive Q means energy is put INTO the system.

Question 14

For an ideal gas, the only internal energy is what? And how is this measured?

Answer 14

Only internal energy in an ideal gas is KE which directly correlates with temperature.

Question 15

For a substance to change state (e.g. liquid to gas) must there by some sort of energy transfer?

Answer 15

Yes, and the total amount of energy between the two are conserved

Question 16

What does isochoric mean?

Answer 16

constant volume (delta V = 0)

Question 17

What does adiabatic mean?

Answer 17

There is no heat transfer (Q = 0)

Question 18

Pressure = ?

Answer 18

Force/Area

Question 19

If a gas exerts pressure on a piston head and moves it, is it doing work?

Answer 19

Yes.

Conversely, contraction of a gas and dropping of a piston head is negative work

Question 20

What is the equation for the work done by an ideal gas (when in a container)

Answer 20

W = P(delta)V

Question 21

In an isochoric process, what is the first law of thermodynamics (eqn)?

Answer 21

(delta)E = Q

The system CANNOT do work because the volume CANNOT change, and thus W = 0

Question 22

What is the equation for an isothermal process (in terms of first law)

Answer 22

Q = W

Since temperature did not change, (delta)E = 0 and it drops out.

Question 23

What is the first law for an adiabatic process?

Answer 23

(delta)E = -W

Question 24

How can you determine/estimate the work done by a system using a P-V diagram?

Answer 24

Work = area under the curve

Question 25

Work on a system = ?

Answer 25

(delta)KE + (delta)PE/ (delta)E

Question 26

What is specific gravity?

Answer 26

Density of fluid/density of water

Question 27

What is gauge pressure?

Answer 27

Difference between surface pressure and at some other point (essentially zeroed to atmosphere).

Question 28

What

is true of weight and buoyant force for a floating object?

Answer 28

W = Fb

density object/density water = volume submerged/volume object

Question 29

Assuming flow speed, v, is constant across area, A, flow = ?

Answer 29

f = Av

flow rate = area x flow speed

Question 30

For an incompressible fluid, is flow rate constant throughout a pipe?

Answer 30

A1v1 = A2v2

Speed is inversely proportional to area

Question 31

What is Bernoulli’s eqn?

Answer 31

P1 + rhogy1 + 1/2rhov1^2 = P2 + rhogy2 + 1/2rhov2^2

P1 + PE1 + KE1 = P2 + PE2 + KE2

Question 32

Work = ?

Answer 32

Force x distance

Question 33

Inside a pump, at a constant height, higher speed (v) = ________ pressure

Answer 33

Lower!

Kinda counterintuitive, right?

Question 34

Is any fluid exposed to the atmosphere the same t all points?

Answer 34

Yes