Chapter 8

hydrogen has a specific gravity of slightly less than...

0.0001. Therefore, if you get a specific gravity value less than about 10 -4 , you need to check your work very carefully.

Absolute pressure

Absolute pressure uses a perfect vacuum as a reference point. Most meteorological readings are given as absolute pressure, using units of atmospheres or bars.

how are absolute pressures distinguished in writing?

Absolute pressures are distinguished by an "a" after the pressure unit, such as "psia" to signify "pound-force per square inch absolute."

Calorie

Amount of heat required to raise the temperature of one gram of water by one degree Celsius

molar mass

Atomic weight = molar mass

Electric current

Charge per amount of time. SI unit is amperes

Density

Density (Greek letter rho) is the mass of an object ( m ) divided by the volume the object occupies ( V ).

Power

Energy per time. The SI unit is watt

Coulomb's Law

F = k Q1Q2/r^2

how are gauge pressures distinguished in writing?

Gauge pressure readings are distinguished by a "g" after the pressure unit, such as "psig" to signify "pound-force per square inch gauge."

gauge pressure

Gauge pressure uses the local atmospheric pressure as a reference point.

mole

If there is (1.66 * 10^-24 g)/(1 amu), then there is (1 amu)/(1.66 * 10^-24 g). Dividing this out gives 6.022 * 10^23 amu/g. This numeric value is used to define the mole [mol].

Note about gas law

Note that we must use absolute temperature units in the ideal gas equation. We cannot begin with relative temperature units and then convert the final answer. Also, all pressure readings must be in absolute, not gauge, units.

Ideal Gas Law

PV = NRT

what is pascals law?

Pascal's law states the hydrostatic pressure of a fluid is equal to the force of the fluid acting over an area

gas constant

R

Inductance

SI unit is henrys

Joule

SI unit of work. Defined as one newton of force acting over a distance of one meter

Specific weight

Specific weight (g, Greek letter gamma) is the weight of an object ( w ) divided by the volume the object occupies ( V )

Rankine scale

The Rankine scale is named for William J. M. Rankine (1820-1872), a Scottish engineer and physicist, who proposed an analogy to the kelvin scale, using the Fahrenheit scale.

Newton

The SI unit of force, the newton [N], is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared

British Thermal Unit (BTU)

The amount of heat required to raise the temperature of one pound-mass of water by one degree fahrenheit.

atomic mass units [amu]

The atomic mass of an atom in atomic mass units [amu] is approximately equal to the number of nucleons it contains

Kelvin scale

The kelvin scale is named for First Baron William Thomson Kelvin (1824-1907), an English mathematician and physicist. Kelvin first proposed the idea of "infinite cold," or absolute zero, in 1848, using the Celsius scale for comparison.

mass

The mass of an object is a fundamental dimension. Mass is a quantitative measure of how much of an object there is, or in other words, how much matter it contains.

specific gravity

The specific gravity (SG) of an object is a dimensionless ratio of the density of the object to the density of water

weight

The weight ( w ) of an object is a force equal to the mass of the object ( m ) times the acceleration of gravity ( g ).

atomic mass unit [amu]

To avoid having to use such tiny numeric values when dealing with nucleons, physicists defined the atomic mass unit [amu] to be approximately the mass of one nucleon. -1 amu = 1.66 * 10^−24 g

molecular mass

Two atoms of hydrogen combine with one atom of oxygen, so 2 * 1 amu H + 16 amu O = 18 amu H2O. The molecular mass of water is 18 amu

Ohm's Law

V = IR

Inductor

a coil of wire

Kinetic Energy

a form of energy possessed by an object in motion.

Potential Energy

a form of work done by moving a weight ( w )—which is a force—a vertical distance ( H ).

Efficiency

a measure of how much of a quantity is lost in a process

Horsepower

a unit of power originally used to quantify how the steam engine could replace the work done by a horse

what is avagadros number?

a value of 6.022 * 10^23 particles per mole

when referring to the measurement of pressure, what are the two types of reference points that are commonly used?

abosulte pressure and gauge pressure

why is avagadros number useful?

affords a conversion path between moles and mass

Output

amount of energy or power or whatever is actually applied to the task itself by the mechanism

Energy

an abstract quantity with several definitions, depending on the form of energy being discussed.

fluid

applies to a gas, such as helium or air, or a liquid, such as water or honey.

atomic weight

atomic weight is used, representing the average value of all isotopes of the element. This is the value commonly listed on periodic tables

why is the SI system coherent?

because the derived unit is set at one by combing base units.

Thermal Energy

energy associated with a change in temperature

Work

energy expended by exertion of a force ( F ) over a distance ( d ).

Rotational Kinetic Energy

energy from the motion of an object spinning in place

Pressure

force acting over an area, where the force is perpendicular to the area

Gas Constant

is R in the ideal gas Law equation. The value can differ with different units of pressure, volume, and temperature, but the standard value for it is .08206 atm L/ mol K

why is it useful to use specific gravity?

it is dimensionless, which means that any unit system may be applied by our choice of the units of the density of water

Dalton [Da]

its just another way to say atomic mass unit

formula weight

molecular weight = formula weight

Energy of Translational Motion

object upon which the force is applied acquires kinetic energy

Capacitance

one coulomb per volt. Stores charge. The book definitions are absolute crap. SI unit is farad

Resistance

one volt per ampere.

what are the densest naturally occurring elements at normal temperature and pressure?

osmium and iridium, both with a specific gravity close to 22.6

Gino:

pages 188-209

Lorenzo:

pages 210-230

The densest substances that a normal person is likely to encounter are...

platinum (SG = 21.5) and gold (SG = 19.3) . Thus, if you calculate a specific gravity to be higher than about 23, you have almost certainly made an error.

Input

quantity of energy or power from some source to operate and accomplish its task

ideal gas law

relates the quantities of pressure ( P ), volume ( V ), temperature ( T ), and amount ( n ) of gas in a closed container: PV = nRT

Voltage

the amount of work required to move an electric charge in the vicinity of other electric charges. SI unit is volts

Electric Charge

the book does not define it in any valuable way whatsoever

Total pressure

the combination of atmospheric and hydrostatic pressure.

Gas pressure

the pressure created by a gas inside a closed container.

Atmospheric pressure

the pressure created by the weight of air above us.

Hydrostatic pressure

the pressure exerted on a submerged object by the fluid in which it is immersed.

According to SI rules, what is the rule concerning units after a "per" (grams per mole)

they go in the denominator: 1g/1mol

true or false: In technical literature, density is rarely given;; instead, the specific gravity is reported.

true

pascal [Pa]

unit of pressure, defined as one newton of force acting on an area of one square meter