Physics

Question 1

What is potential energy?

Answer 1

Energy associated with position in space

Question 2

What is the kinetic energy equation?

Answer 2

K = 1/2(m)(v^2)

Question 3

What is the datum?

Answer 3

The zero potential energy position defined in a given problem

Question 4

What is the gravitational potential energy eqn?

Answer 4

U = mgh

Question 5

What is the eqn for elastic potential energy?

Answer 5

U = 1/2(k)(x^2)q

Question 6

What is total mechanical energy?

Answer 6

Sum of the potential and kinetic energies

E = U + K

Question 7

What is a conservative force?

Answer 7

A force that is path independent and does not dissipate energy.

EX: gravitational and electrostatic (and frictionless elastic)

Question 8

What is the general equation for work done on a system?

Answer 8

W = [U final - U init.] + [K final - K init.]

Question 9

Define work

Answer 9

the process by which energy is transferred from one system to another; NOT A FORM OF ENERGY, even though it is measured in joules

Question 10

What is the eqn for work done by a force?

Answer 10

W = F (d) (cos theta) or W = F * d (dot product)

Question 11

What is a P-V graph?

Answer 11

A graphical representation of gas expansion and compression w/ volume on x-axis and pressure on y-axis

Question 12

What is a isovolumetric or isochoric process?

Answer 12

A process by which pressure changes but volume stays the same: no work is done.

Question 13

What is a isobaric process?

Answer 13

A process by which volume changes but pressure stays the same: W = P(delta V)

Question 14

Define power

Answer 14

rate of energy transfer from one system to another

Question 15

What is the equation for power?

Answer 15

P = W/t = (delta E)/t

Question 16

What is the unit for power?

Answer 16

Watt

J/s

Question 17

What is a Joule in base units?

Answer 17

kg(m^2)/(s^2)

Question 18

What’s the eqn for calc mechanical work without knowing displacement or forces?

Answer 18

W net = delta K

Question 19

What is mechanical advantage?

Answer 19

the ratio of force input applied to machine to force output for machine

MA = F out/ F in

Question 20

What is the efficiency eqn?

Answer 20

Efficiency = W out/ W in = [(load)(load distance)]/[(effort)(effort distance)]

Question 21

define energy

Answer 21

the property that enables a system to enable to do something like do work

Question 22

What is the zeroth Law of Thermodynamics?

Answer 22

In thermal systems, if a = b, and b = c, then a = c

Question 23

Define temperature

Answer 23

Relative proportion of the average kinetic energy of the particles that make up the substance

Question 24

How do you get K degrees from C degrees?

Answer 24

K = C + 273.15

Question 25

What is the freezing point of water? Boiling point?

Answer 25

0 C (273.15 K) and 100 C (373.15 K) respectively

Question 26

What is the 3rd Law of Thermodynamics?

Answer 26

the entropy of a perfectly organized crystal at 0 K is absolute zero

Question 27

What is the formula for changing Celcius to Farenheit?

Answer 27

F = 9/5 (C) + 32

Question 28

What is the eqn for linear thermal expansion? (used for thermometers or any rod shaped solids)

Answer 28

delta L = alpha(L)(delta T) alpha is the coefficient of linear expansion of a specific material

Question 29

What is the eqn for volumetric thermal expansion? (used for liquids and solids)

Answer 29

delta V = beta(V)(delta T) beta is the coefficient of volumetric expansion of a specific material

Question 30

Define isolated system

Answer 30

a system that is not capable of exchanging energy or matter with it's surroundings

Question 31

Define closed system

Answer 31

a system that can exchange energy, but not matter, with it's surroundings

Question 32

Define open system

Answer 32

a system that can exchange both energy and matter with it's surroundings

Question 33

What is a state function?

Answer 33

a thermodynamic property that is a function of the equilibrium state currently experienced, regardless of the path taken to get there

Question 34

What are the 8 state functions?

Answer 34

pressure, density, temperature, volume, enthalpy, internal energy, Gibbs free energy, and entropy

Question 35

What is a process function? What are 2 examples?

Answer 35

a thermodynamic property that is dependent on the path taken to get there work and heat

Question 36

What is the 1st Law of Thermodynamics?

Answer 36

The change in total energy of a system is equal to the heat transferred into the system minus the work done by the system delta U = Q - W

Question 37

What does a positive delta U mean in thermodynamics? What about a positive Q? What about a positive W?

Answer 37

+ U means temperature has increased +Q means heat is flowing into the system + W means work is being done by the system on the surroundings

Question 38

What is the 2nd Law of Thermodynamics?

Answer 38

Before equalibrium, objects in contact will experience heat transfer

Question 39

How many joules are in a Calorie? How many BTU's?

Answer 39

4184 J = 1000 cal = 1 Cal = 3.97BTU

Question 40

Define conduction

Answer 40

direct transfer of heat through molecular collisions

Question 41

Define convection

Answer 41

indirect transfer of heat through fluid flow (only liquids or gases)

Question 42

Define radiation

Answer 42

the transfer of heat by electromagnetic waves (can be done through a vaccum)

Question 43

What is specific heat?

Answer 43

the amount of energy required to heat 1 g of a substance 1 K or 1 C (same difference)

Question 44

What is the specific heat equation?

Answer 44

q = sm(delta T)

Question 45

What is the eqn for heat change during a phase change?

Answer 45

q = m(heat of transformation) | can't use qsmAt because there is no temp change

Question 46

Define an adiabatic process

Answer 46

a process where heat transfer is 0

Question 47

Define an isothermal process

Answer 47

a process where temperature change = 0

Question 48

define entropy

Answer 48

a measure of how widely dispersed the energy becomes at a certain temperature

Question 49

What is the eqn for calculating entropy?

Answer 49

delta S = Qrev/T Qrev is heat change in a reversible process

Question 50

What are the units for entropy?

Answer 50

J/(mol*K)

Question 51

Define an irreversible process

Answer 51

A process that does not spontaneously return to it's previous state (also called a natural process)

Question 52

Define a reversible process

Answer 52

A process that does spontaneously return to it's previous state (also called an unnatural process because energy would have to be completely conserved in this process, which is not possible)