Exam 1 Ch.1-3

Question 1

Thermodynamics

Answer 1

The science of energy

Question 2

Energy

Answer 2

The ability to cause changes

Question 3

Conservation of energy principle

Answer 3

During an interaction, energy can change from one form to another, but the total amount of energy remains constant. That is, energy cannot be created or destroyed.

Question 4

Change in E

Answer 4

Change in E = Ein - Eout

Question 5

First law of thermodynamics

Answer 5

An expression of the conservation of energy principle, it asserts that energy is a thermodynamic property

Question 6

Second Law of thermodynamics

Answer 6

Asserts that energy has quality as well as quantity, and actual processes occur in the direction of decreasing quality of energy

Question 7

Classical Thermodynamics

Answer 7

A macroscopic approach to the study of thermodynamics that does not require a knowledge of the behavior of individual particles. It provides a direct and easy way to solve engineering problems.

Question 8

Units

Answer 8

Magnitudes assigned to dimensions

Question 9

Dimensions

Answer 9

Any physical quantity

Question 10

Derived units

Answer 10

velocity, energy, volume, expressed in terms of the primary dimensions and are called secondary dimensions or derived dimensions

Question 11

Primary / Fundamental dimensions

Answer 11

length (meter), mass (kilogram), time (second), temperature (kelvin), electric current (ampere), amount of light (candela), amount of matter (mol)

Question 12

pound-force (lbf)

Answer 12

the force required to accelerate a mass of 1 slug at a rate of 1 ft/s^2

Question 13

Weight

Answer 13

he gravitational force applied to a body, its magnitude is determined from Newton’s Second Law, W=m*g where m is mass, g is the gravitational acceleration (g is 9.807 m/s^2 or 32.174 ft/s^2

Question 14

Work

Answer 14

A form of energy, can simply be defined as force times distance

Question 15

Joule

Answer 15

= 1 N*m

Question 16

BTU (British Thermal Unit)

Answer 16

The energy required to raise the temperature of 1 lbm of water at 68F by 1F.

Question 17

Calorie

Answer 17

the amount of energy needed to raise the temperature of 1g of water at 14.5C by 1C.

Question 18

Watt

Answer 18

J/s, unit for time rate of energy, in the case of work, the time rate of energy is called power

Question 19

1 kg m/s^2

Answer 19

Newton

Question 20

Surroundings

Answer 20

The mass or region outside the system

Question 21

Boundary

Answer 21

The real or imaginary surface that separates the system from its surroundings (can be fixed or movable) Has zero thickness

Question 22

Closed System (Control Mass)

Answer 22

Consists of a fixed amount of mass, and no mass can cross its boundary, no mass can enter or leave. Energy in the form of heat or work can cross the boundary and the volume does not have to be fixed.

Question 23

Isolated system

Answer 23

Closed system where energy is not allowed to cross the boundary

Question 24

Open system (Control volume)

Answer 24

Usually encloses a device that involves mass flow such as a compressor, turbine, or nozzle. Both mass and energy can cross the boundary of a control volume.

Question 25

Property

Answer 25

Any characteristic of a system Ex: pressure, temp, volume, mass, viscosity, thermal conductivity, etc.

Question 26

Intensive properties

Answer 26

Properties independent of the mass of a system, such as temperature, pressure, and density

Question 27

Extensive Properties

Answer 27

Properties that depend on the size - or extent - of the system. Total mass, total volume, total momentum

Question 28

Specific Properties

Answer 28

Extensive properties per unit mass Ex: specific volume

Question 29

Continuum

Answer 29

Continuous, homogeneous matter with no holes

Question 30

Density

Answer 30

Mass per unit volume

Question 31

Specific Volume

Answer 31

The reciprocal of density, volume per unit mass

Question 32

Specific Gravity (Relative density)

Answer 32

the ratio of the density of a substance to the density of some standard substance at a specified temperature

Question 33

State

Answer 33

A set of properties that completely describes the condition of the system at a specific time

Question 34

Equilibrium

Answer 34

Implies a state of balance. There are no unbalanced potentials or driving forces within the system