Transcript Test #3 Review

The Four Energy Systems
Mechanical
Fluid
Electrical
Thermal
The Prime Movers of the
Four Energy Systems
Mechanical
- Force
Fluid- Pressure
Electrical- Voltage
Thermal- Temperature
“Work” in a
Mechanical Energy System
Mechanical
work happens when
forces or torques cause objects to
move.
 Work = Force X Distance
 Work = Torque X Angle
“Work” in a
Fluid Energy System
In
Fluid systems, work is done
when a pressure difference
causes liquids or gases to move.
 Work = Pressure X Volume
“Work” in a
Fluid Energy System
Work
occurs in a fluid system when
fluid pressure p causes a given
volume (v) of liquids or gases to
move.

W = p X (v)
“Work” in a
Fluid Energy System
Work
occurs in a fluid system when a
fixed volume of fluid v moves through
a pressure difference (p).

W = (p) X v
What is Mechanical Work?
Work in a mechanical system
involves two parts.
An applied force must act on an
object.
The object must move while the
force is applied.
What is Energy?
ENERGY is the ability to do WORK
To
cause something to MOVE!
ENERGY is the ability to cause Change
Living things cannot work without Energy, and
machines cannot work without Energy.
What is Energy?
You
cannot get no more Work out of a
Machine then the ENERGY you put into it.
Due to FRICTION, the WORK produced is
usually less than the Energy used.
What is Energy?
Energy
cannot be created or destroyed.
Forms of ENERGY can be transferred from
one form to another.
The use of Energy and the lost of Energy
usually ends up as HEAT.
How do you define the amount
of work being done?
The
force applied in the direction
of the motion of the object times
the distance the object moves
while the force is acting.
Name Six Simple Machines?
Lever
Pulley
Wheel
& Axle
Inclined Plane
Wedge
Screw
Lever
Every Lever has three (3) parts:
A. Resistance Force or Load, What you are
trying to move or lift.
B. Effort Force - The Work done on the Lever.
C. Fulcrum – A fixed pivot point.
Three Types of Levers
The position of the fulcrum in
relation to the applied force
determines the lever class
Three Types of Levers
Pulley
A fixed pulley has no mechanical advantage.
It only changes direction.
Pulley
Mechanical Advantage
A movable pulley has mechanical advantage based
upon how many supporting strands.
Pulley
Mechanical Advantage
Wheel & Axle
Incline Plane
Inclined Plane
Wedge
Wedge
Screw
Screw
Open Systems
In open systems, matter may flow in and out of
the system boundaries. The first law of
thermodynamics for open systems states: the
increase in the internal energy of a system is
equal to the amount of energy added to the
system by matter flowing in and by heating, minus
the amount lost by matter flowing out and in the
form of work done by the system.
Open Systems
This type of system uses wells or a body of water as the source of heat
exchange fluid that circulates directly through a heat exchanger in the
building. Once it has circulated through the heat exchanger, the water
returns to the ground through the recharge well or the body of water.
Closed Systems
A closed systems can exchange heat and work,
but not matter, with it’s surroundings.
Closed Systems
Closed/Pond Loop System
Since water transfers heat much better than soil, closed loop systems are
often located in lakes or ponds by submerging GeoExchange loop coils in the
water.
Information can be found on
the class web site.
Information can be found on
the class web site.
Information can be found on
the class web site.