Mastery Learning - First Law

draweryaleMechanics

Oct 27, 2013 (3 years and 7 months ago)

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Mastery Learning
-

First Law
of Thermodynamics &
Energy Balance

email:
drjjlanita@hotmail.com

jjnita@salam.uitm.edu.my

Website: http://www5.uitm.edu.my/faculties/fsg/drjj1.html

Applied Sciences Education Research
Group (ASERG)

Faculty of Applied Sciences

Universiti Teknologi MARA

Voice: 019
-
455
-
1621

Quotes

"
One who learns by finding out has
sevenfold the skill of the one who learned
by being told.“
-

Arthur Gutterman


"
The roots of education are bitter, but
the fruit is sweet."
-
Aristotle

Advantages

Disadvantages
(easily dealt with)

Preparation


Teachers must
state objectives
before designating
activities


Requires teachers
to do task analysis,
thereby becoming
better prepared to
teach the unit.


Students progress
at different pace;
so students who
have mastered
must wait for those
who haven’t or
must individualize
instruction.


Must have a
variety of
materials for re
-
teaching.


Teacher must state
objectives clearly.


Teacher must
perform task
analysis.

Instructional Strategy
-

Mastery Learning

Advantages

Disadvantages

Preparation


Requires teachers
to state objectives
before designating
activities


Can break cycle of
failure (especially
important for
minority and
disadvantaged
students)


Must have several
tests for each unit


If only objective
tests are used, can
lead to
memorizing and
learning specifics
rather than higher
levels of learning


Teacher must be
alert and patient in
dealing with the
pace of the pupils.

Instructional Strategy
-

Mastery Learning



First Law of
Thermodynamics & Energy
Balance


Control Mass,
Open System

email:
drjjlanita@hotmail.com

jjnita@salam.uitm.edu.my

Website: http://www5.uitm.edu.my/faculties/fsg/drjj1.html

Applied Sciences Education Research
Group (ASERG)

Faculty of Applied Sciences

Universiti Teknologi MARA

Voice: 019
-
455
-
1621

CHAPTER

4


The First Law of
Thermodynamics

Introduction

1.
Identify the energies causing a system’s
properties to change.

2.
Identify the energy changes within the system.

3.
State the conservation of energy principle.

4.
Write an
energy balance

for a general system
undergoing any process.

Objectives:

Introduction

5.
Write the
unit
-
mass basis

and
unit
-
time basis
(or rate
-
form basis)

energy balance for a general
system undergoing any process.

6.
Write the energy balance in terms of all the
energies causing the change and all the energy
changes within the system.

7.
Write a
unit
-
mass basis

and
unit
-
time basis (or
rate
-
form basis)

energy balance in terms of all
the energies causing the change and all the
energy changes within the system.

Objectives:

Introduction

8.
State the conditions for
stationary, closed
system

and rewrite the energy balance and the
unit
-
mass basis energy balance for stationary
-
closed systems.

9.
Apply the energy conservation principle for a
stationary, closed system

undergoing an
adiabatic

process and discuss its physical
interpretation.

Objectives:

Introduction

10.
Apply the energy conservation principle for a
stationary, closed system

undergoing an
isochoric, isothermal, cyclic and isobaric
process and discuss its physical interpretation.

11.
Give the meaning for specific heat and state its
significance in determining internal energy and
enthalpy change for ideal gases, liquids and
solids.

12.
Use the energy balance for problem solving.

Objectives:

Instructional Plan
-
Mastery

Unit 1:

Objectives:

1.
Identify the energies causing the system to
change.

2.
Identify the energy changes within the system.

3.
State the conservation of energy principle.

4.
Write an
energy balance

for a general system
undergoing any process.

Instructional Plan
-
Mastery

Unit 2:

Objectives:

5.
Write the
unit
-
mass basis

and
unit
-
time basis
(or rate
-
form basis)

energy balance for a general
system undergoing any process.

6.
Write the energy balance in terms of all the
energies causing the change and the energy
changes within the system.

7.
Write a
unit
-
mass basis

and
unit
-
time basis (or
rate
-
form basis)

energy balance in terms of all
the energies causing the change and the energy
changes within the system.

Instructional Plan
-
Diagnose

Preparatory Diagnostics

If P = 100 kPa, T = 25

C

, determine the phase

of water, its specific volume, its specific enthalpy

and its specific internal energy.

How can you boil the water? What types of energy
can you give to boil it? What is the boiling or
saturation temperature?

What is the phase, the specific volume and the
specific internal energy when the temperature
reaches 150

C

, at constant pressure?

Instructional Plan
-

Re
-
teach

Preparatory Diagnostics

Students’ activity
:

read the saturated
-
water,

pressure property table. Obtain


and u.

Students’ activity:

Check table for the saturation temp at
100 kPa. Then suggests 2 ways of boiling water.

Students’ activity:

Suggest the phase and provide
reason. Then suggest method on how to find


and u.

Failure to complete task: re
-
teach then give different
example

Otherwise, proceed with the lesson’s learning outcome

3
-
1

Instructional Plan
-

Re
-
teach

Lem

Oven

200

C

Nasi

Lemak20

C


in

H
2
O:

Sat. Liq.

Sat. Vapor

P = 100 kPa

T = 99.6

C

Q
in

What happens to

the properties of

the system after the

energy transfer?

SODA

5

C

SO䑁

5

C


in

q
out

25

C

Teacher Activity

Energy transfer
-
Thermal (heat)

Example: A steam power cycle.

Steam

Turbine

Mechanical Energy

to Generator

Heat

Exchanger

Cooling Water

Pump

Fuel

Air

Combustion

Products

System Boundary

for Thermodynamic

Analysis

Q
out

W
in

W
out

Q
in

The net work output is

Desired

output

Required

input

Teacher
Activity

Instructional Plan
-

Re
-
teach

Energy Transfer


Work Done

i

Voltage, V

No heat transfer

T increases

after some time

H
2
O:

Super

Vapor

Mechanical work:

Piston moves up

Boundary work is

done by system

Electrical work is done on system

H
2
O:

Sat. liquid

W
pw,in

,kJ

W
e,in

= Vi

琯㄰〰Ⱐ1J

Teacher
Activity

Copyright © The McGraw
-
Hill Companies, Inc. Permission required for reproduction or display.

4
-
8

FIGURE 4
-
46

Pipe or duct flow may
involve more than one
form of work at the
same time.

Teacher
Activity

First Law


Energy Transfer

System in thermal
equilibrium


System

Total energy

E
1


Can it change?
How? Why?

System’s initial total
energy is

E
1
= U
1
+KE
1
+PE
1

or

e
1
= u
1
+ke
1
+pe
1
, kJ/kg

Teacher
Activity

First Law


Energy Transfer

A change has taken
place.


System,

E
1



System

E
1
= U
1
+KE
1
+PE
1

Movable boundary
position gone up

System
expands

Teacher
Activity

First Law


Energy Transfer

A change has taken place


System,

E
1



System


System

Initial

Final

System’s final energy is E
2
=U
2
+KE
2
+PE
2

E
1
= U
1
+KE
1
+PE
1

Movable boundary
position gone up

System

expands

Teacher
Activity

First Law


Energy Transfer

How to relate
changes to
the cause

Heat as a cause
(agent) of change



System

E
1
, P
1
, T
1
, V
1

To


q
in
, or
Q
in

q
out
, or
, Q
out

Properties will change
indicating change of
state

E
2
, P
2
, T
2
, V
2

Teacher
Activity

First Law


Energy Transfer

Work as a cause
(agent) of change



System

E
1
, P
1
, T
1
, V
1

To


Properties will change
indicating change of
state

W
in
,


in
, kJ/kg

W
out
,


in
, kJ/kg

How to relate
changes to
the cause

E
2
, P
2
, T
2
, V
2

Teacher
Activity

First Law


Energy Transfer

How to relate
changes to
the cause

Mass transfer as a
cause (agent) of
change



System

E
1
, P
1
, T
1
, V
1

To


Properties will change
indicating change of
state

Mass
out

Mass
in

E
2
, P
2
, T
2
, V
2

Teacher
Activity

First Law


Energy Transfer

How to relate
changes to
the cause

Dynamic Energies
as causes (agents)
of change



System

E
1
, P
1
, T
1
, V
1

To


Properties will change
indicating change of
state

Mass
out

Mass
in

W
in

W
out

Q
in

Q
out

E
2
, P
2
, T
2
, V
2

Teacher
Activity

First Law
-
Conservation of Energy Principle

Energy must be conserved in any process.
Energy cannot be created nor destroyed. It
can only change forms. Total Energy
before a process must equal total energy
after process

Known as Conservation of Energy Principle

In any
process,
every bit
of energy
should be
accounte
d for!!

z =h

z =0

z =h/2

E=U+KE+PE = U+0+PE

Teacher
Activity

First Law
-
Conservation of Energy Principle

Energy must be conserved in any process.
Energy cannot be created nor destroyed. It
can only change forms. Total Energy
before a process must equal total energy
after process

Known as Conservation of Energy Principle

In any
process,
every bit
of energy
should be
accounte
d for!!

z =h

z =0

z =h/2

E=U+KE+PE

E=U+KE+PE=U+
0
+PE

Teacher
Activity

First Law
-
Conservation of Energy Principle

Energy must be conserved in any process.
Energy cannot be created nor destroyed. It
can only change forms. Total Energy
before a process must equal total energy
after process

Known as Conservation of Energy Principle

In any
process,
every bit
of energy
should be
accounte
d for!!

z =h

z =0

z =h/2

E=U+KE+PE

E=U+KE+
0


Teacher
Activity

First Law Energy Balance

Energy Balance




Amount of
energy causing
change

must be equal to

amount
of
energy change

of system

Energy
Entering
a system


-

Energy
Leaving
a system


=

Change of
system’s
energy

Teacher
Activity

First Law of Thermodynamics

Energy Balance




E
in



E
out

=

E
sys
, kJ or

e
in



e
out

=

e
sys
, kJ/kg or

Energy
Entering
a system


-

Energy
Leaving
a system


=

Change of
system’s
energy

Teacher
Activity

First Law of Thermodynamics

How to relate
changes to
the cause

Dynamic Energies
as causes (agents)
of change



System

E
1
, P
1
, T
1
, V
1

To

E
2
, P
2
, T
2
, V
2

Properties will change
indicating change of
state

Mass
out

Mass in

W
in

W
out

Q
in

Q
out

Teacher
Activity

Copyright © The McGraw
-
Hill Companies, Inc. Permission required for reproduction or display.

4
-
1

FIGURE 4

7

The energy change of
a system during a
process is equal to the
net
work and heat
transfer between the
system and its
surroundings.

Teacher
Activity

Instructional Plan
-
Activity

Active Cooperative (group) Learning

Name the energies which are agents of change

Name the energies within a system.

Draw and label energy interacting with a system
and the energy changes within a system

Student
Activity

Draw the energies interacting with an open system

State the general energy conservation principle

Quantitatively solve some numerical problems

Instructional Plan
-

Assess

Active Cooperative (group) Learning

Failure to complete task: re
-
teach then give different
example

Otherwise, proceed with the next unit

Teacher
-
students
Activity

If all ok, increase difficulty level to application, analysis,
synthesis and evaluation

Instructional Plan
-
Mastery

Unit 2:

Objectives:

5.
Write the
unit
-
mass basis

and
unit
-
time basis
(or rate
-
form basis)

energy balance for a general
system undergoing any process.

6.
Write the energy balance in terms of all the
energies causing the change and the energy
changes within the system.

7.
Write a
unit
-
mass basis

and
unit
-
time basis (or
rate
-
form basis)

energy balance in terms of all
the energies causing the change and the energy
changes within the system.

First Law


Interaction Energies

Energy Balance


The
Agent

E
in

= Q
in
+W
in
+E
mass,in

,kJ

e
in

= q
in
+

in
+
q
in
, kJ/kg

Teacher
Activity

First Law
-

Interaction Energies

Energy Balance


The
Agent

E
out

= Q
out
+W
out
+E
mass,out

,kJ

e
out

= q
out
+

out
+
q
out
, kJ/kg

Teacher
Activity

First Law
-

System’s Energy

Energy Balance


The Change
WIthin

Energy change within the system,

E
sys
= E
2
-
E
1

Internal energy change,

U = U
2



U
1

kinetic energy change,

KE = KE
2



KE
1

potential energy change,

PE = PE
2



PE
1

is the sum of

Teacher
Activity

First Law


Energy Change

Energy Balance


The Change
WIthin


E
sys

=

U+

KE+

PE, kJ


e
sys

=

u+

ke
+

pe, kJ/kg

Teacher
Activity

First Law


General Energy Balance

Energy Balance




E
in



E
out

=

E
sys
, kJ or

e
in



e
out

=

e
sys
, kJ/kg or

Energy
Entering
a system


-

Energy
Leaving
a system


=

Change of
system’s
energy

Teacher
Activity

First Law


General Energy Balance

Energy Balance

General
system

Q
in
+ W
in
+ E
mass,in


Q
out


W
out
-

E
mass,out


q
in
+

in
+
q
in


q
out



out


q
out

=

U+

KE

+

PE, kJ

=

u+

ke

+

pe, kJ/kg

Teacher
Activity

Instructional Plan
-
Activity

Active Cooperative (group) Learning

Student
Activity

Write an energy balance representing the net
interacting energies (agents of change) and the
energy changes in the system

Write an energy balance in unit mass form,
representing the net interacting energies (agents
of change) and the energy changes in the
system

Write an energy balance in unit time form or rate
form, representing the net interacting energies
(agents of change) and the energy changes in
the system

Instructional Plan
-

Assess

Active Cooperative (group) Learning

Failure to complete task: re
-
teach then give different
example

Otherwise, proceed with the next unit

Teacher
-
students
Activity

If all ok, increase difficulty level to application, analysis,
synthesis and evaluation