Lecture 2 / ENERGY Flashcards

1
Q

can exist as thermal, mechanical, kinetic, potential, electric, magnetic, chemical and nuclear. Their sum constitutes the total energy E of the system. e = u + ke + pe = u + V²/2 + gz (kJ/kg)

A

total energy

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2
Q

a system possesses as a whole with respect to some outside reference frame, such as kinetic and potential energies.

A

macroscopic forms of energy

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3
Q

related to the molecular structure of a system and the degree of the molecular activity, independent of the outside reference frames.

A

microscopic forms of energy

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4
Q

The sum of all the microscopic forms of energy, denoted by U.

A

internal energy

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5
Q

is the energy that a system possesses as a result of its motion relative to some reference frame. When all parts of a system move at the same velocity,

A

kinetic energy

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6
Q

is the energy that a system possesses as a result of its elevation in a gravitational field.

A

potential energy

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7
Q

____________ whose velocity and elevation of the **centre of gravity remain constant **during a process are often referred to as _____________

A

closed systems , Stationary systems

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8
Q

The amount of mass flowing through a cross section per unit time. ṁ = ρV̇

A

mass flow rate ṁ

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9
Q

The flow of thermal energy from higher temperature to lower temperature via conduction, convection and radiation.

A

heat transfer

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10
Q

is equal to force multiplied by displacement.

A

work

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11
Q

highest quality of energy, for example, can always be converted to an equal amount of thermal energy ( also called heat )

A

ELECTRICITY

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12
Q

can exist in numerous forms such as thermal, mechanical, kinetic, potential, electric, magnetic, chemical, and nuclear, and their sum constitutes the total energy E of a system

A

ENERGY

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12
Q

typically involve fluid flow for long periods of time, and it is convenient to express the energy flow associated with a fluid stream in the rate form

A

CONTROL VOLUMES

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13
Q

the form of energy that can be converted to mechanical work completely and directly by an ideal mechanical device such as an ideal turbine

A

MECHANICAL ENERGY

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14
Q

energies are the familiar forms of mechanical energy.

A

KINETIC AND POTENTIAL

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15
Q

Is defined as the form of energy that is transferred between two systems ( or a system and its surroundings ) by virtue of temperature difference.

16
Q

A process during which there is** no heat transfer** is called an ____________

A

Adiabatic process

17
Q

Is a energy interaction between a system and its surroundings

18
Q

conservation of the quality of energy, not the quantity

A

Energy Conservation

19
Q

The magnetic, electric, and surface tension effects are significant in some specialized cases only and are usually ignored

A

total energy of a system

20
Q

Motion of a particle system

A

Sensible energy

21
Q

Phase change

22
Q

__________can cross the boundary of a
closed system in two distinct forms:_____________

A

Energy ; heat and work

23
Q

is energy in transition. It is
recognized only as it crosses the
boundary of a system

24
have inexact differentials designated by the symbol δ. differential amount of heat or work is represented by δQ or δW, respectively, instead of dQ or dW
Path functions
25
The net change (increase or decrease) in the total energy of the system during a process is equal to the difference between the total energy entering and the total energy leaving the system during that process
ENERGY BALANCE
26
An energy interaction that is not caused by a temperature difference between a system and its surroundings is work
Work Transfer, W
27
the system serves as an additional mechanism of energy transfer. When mass enters a system, the energy of the system increases because mass carries energy with it
Mass flow
28
Thermodynamics provides no information about the absolute value of the total energy. It deals only with the __________________, which is what matters in engineering problems
change of the total energy
29