Sprung Weight; The Eqn of Motion for Vehicle Suspension

[Bret Cahill]

Check this out, especially the forcing function that increases with
mass.

To keep things simple assume a motor vehicle consists of 2 masses
connected by a spring with const. k and a shock with const c. Call
the body, frame, engine etc. one mass, m1 and the suspension is the
spring + shock and the wheels are m2.

When there is a forcing function P(t) on m2, which increases linearly
with m2, the equation of motion, derived from summing all the forces
on each mass is:

m1x1''(t) + c(x1'(t) - x2'(t)) + k(x1(t) - x2(t)) = 0

m2x2''(t) + c((x2'(t)-x1'(t)) + k(x2(t) - x1(t)) = m2P(t)

x(t), x'(t) and x"(t) are displacement, velocity and acceleration of
each mass respectively.

Adding both equations:

m1x1''(t) + m2x2''(t) = m2P(t)

or

x1"(t) = [m2P(t) - m2x2"(t)] / m1 = m2 (P(t) - x2"(t)) / m1

x1''(t) is the acceleration on the chassis.

The more you increase m2 [heavy wheels] and decrease m1, the more you
increase x1''(t), the acceleration on m1.

The short qualitative answer:

The harder you hit the pot hole the harder pothole hits back.
Why duke it out with a pothole?

That's one argument for shifting weight from the wheels to above the
suspension.

The other argument is heavy wheels increase the energy necessary to
get what is basically a flywheel up to speed.

Go to a bike shop and try a really nice $700 racing bicycle. Compared
to a beach cruiser, when you step down on the pedal it almost leaps
ahead.


Bret Cahill

 

[john joseph]

Bret Cahill wrote:

The short qualitative answer:

The harder you hit the pot hole the harder pothole hits back.
Why duke it out with a pothole?

That's one argument for shifting weight from the wheels to above the
suspension.

It's no big deal. If the required torque/work is distributed among all
four wheels, the weight of each can be less (less motor) and the sum
energy will be made and handling will be better.

Go to a bike shop and try a really nice $700 racing bicycle. Compared
to a beach cruiser, when you step down on the pedal it almost leaps
ahead.

I have a $3,400 bicycle and a pristine 1949 cruiser - it's all about
total weight of everything in that case (and better bearing technology).

 

[Bret Cahill]

Another way to look at it is, if you have a large mass at one end of a
spring and a small one at the other, which one would you rather shake
to keep the other from moving so much?

The short qualitative answer:

The harder you hit the pot hole the harder pothole hits back.
Why duke it out with a pothole?

Also the heavier the wheels the harder it'll be for the spring to
accelerate the wheels to keep contact with the road.

x2"(t) = [m2P(t) - m1x1"(t)] / m2

That's one argument for shifting weight from the wheels to above the
suspension.

It's no big deal. If the required torque/work is distributed among all
four wheels, the weight of each can be less (less motor) and the sum
energy will be made and handling will be better.

At the rate fuel prices are soaring a bad or even somewhat dangerous
ride will soon be a moot issue. The pre peak oil consumer society and
Ralph Nader are quickly becoming distant memories.

The typical motorist would rather ride in the back of a flatbed truck
than pay $20/gallon for fuel.

Go to a bike shop and try a really nice $700 racing bicycle. Compared
to a beach cruiser, when you step down on the pedal it almost leaps
ahead.

I have a $3,400 bicycle and a pristine 1949 cruiser - it's all about
total weight of everything in that case (and better bearing technology).

Try a road or criterium bike with heavy training wheels then lighter
racing wheels.


Bret Cahill

 

[Bret Cahill]

Extra credit: Set this up for active suspension:

Check this out, especially the forcing function that increases with
mass.

To keep things simple assume a motor vehicle consists of 2 masses
connected by a spring with const. k and a shock with const c. �Call
the body, frame, engine etc. one mass, m1 and the suspension is the
spring + shock and the wheels are m2.

When there is a forcing function P(t) on m2, which increases linearly
with m2, the equation of motion, derived from summing all the forces
on each mass is:

m1x1''(t) + c(x1'(t) - x2'(t)) + k(x1(t) - x2(t)) = 0

m2x2''(t) + c((x2'(t)-x1'(t)) + k(x2(t) - x1(t)) = m2P(t)

x(t), x'(t) and x"(t) are displacement, velocity and acceleration of
each mass respectively.

Adding both equations:

m1x1''(t) + m2x2''(t) = m2P(t)

or

x1"(t) = [m2P(t) - m2x2"(t)] / m1 = m2 (P(t) - x2"(t)) / m1

x1''(t) is the acceleration on the chassis.

The more you increase m2 [heavy wheels] and decrease m1, the more you
increase x1''(t), �the acceleration on m1.

The short qualitative answer:

The harder you hit the pot hole the harder pothole hits back.
Why duke it out with a pothole?

That's one argument for shifting weight from the wheels to above the
suspension.

The other argument is heavy wheels increase the energy necessary to
get what is basically a flywheel up to speed.

Go to a bike shop and try a really nice $700 racing bicycle. �Compared
to a beach cruiser, when you step down on the pedal it almost leaps
ahead.

Bret Cahill

 

[john joseph]

Bret Cahill wrote:

The typical motorist would rather ride in the back of a flatbed truck
than pay $20/gallon for fuel.

LOL! Good image.

Sure! And public transportation should become more popular. You would
think. Anyway, I fretted over dependency upon transportation, the
insurance and energy and auto expenses then lucked out to find a job
less than a mile from home, so I ride a bicycle or walk year-around (in
Minnesota!)

READ THIS - in 1994, electric motors accounted for about 25% of the
total use of online electricity in the USA. What are the consequences of
having millions of electric vehicles on the road? More power plants,
more nukes (about time)??? Dunno.

 

[john joseph]

Bret Cahill wrote:

Extra credit: Set this up for active suspension:

Look way back to 1960-something when the Citroen sedan had active
suspension - hydraulic controlled. No electronics required.

 

[T. Keating]

On Thu, 4 Jun 2009 09:58:48 -0700 (PDT), Bret Cahill
<BretCahill@peoplepc.com> wrote:

Check this out, especially the forcing function that increases with
mass.

snip..

The other argument is heavy wheels increase the energy necessary to
get what is basically a flywheel up to speed.

Go to a bike shop and try a really nice $700 racing bicycle. Compared
to a beach cruiser, when you step down on the pedal it almost leaps
ahead.

Low rolling resistance of HP (80-100 psi) tires makes a world
difference.

If you have the rims for it, refit your mountain bike tires with High
pressure tires.. You'll be amazed..

http://www.maxxis.com/Bicycle/Urban/Hookworm.aspx
http://www.maxxis.com/Bicycle/Training-Tires/Detonator.aspx

Start with the rear tire.. It carries most of the weight and generates
most of the rolling resistance.

 

On Jun 5, 8:17 am, john joseph <nowh...@nowhere.nl> wrote:

Bret Cahill wrote:
The typical motorist would rather ride in the back of a flatbed truck
than pay $20/gallon for fuel.

LOL! Good image.

Sure! And public transportation should become more popular. You would
think. Anyway, I fretted over dependency upon transportation, the
insurance and energy and auto expenses then lucked out to find a job
less than a mile from home, so I ride a bicycle or walk year-around (in
Minnesota!)

READ THIS - in 1994, electric motors accounted for about 25% of the
total use of online electricity in the USA. What are the consequences of
having millions of electric vehicles on the road? More power plants,
more nukes (about time)??? Dunno.

Start with a universal regulation that utilities must buy power from
consumers at a fair rate. There are plenty of commercial buildings
that can take a wind generator or solar panels on the roof, to begin
with. Then put generators of whatever kind along all the highways and
interstates---that way Bret's plan for highway electrification will
have a head start when the politics catches up with him.

Distributed production is like having the 4 motors instead of one---
the market will drive innovation and improvement much faster.

-tg

 

[Bret Cahill]

The typical motorist would rather ride in the back of a flatbed truck
than pay $20/gallon for fuel.

LOL! Good image.

Sure! And public transportation should become more popular.

Most would prefer to drive a flatbed _from the bed_ than take a bus.

Post peak survival society just isn't going to be much like pre peak
consumer society. Sprung weight issues will be like setting up lawn
chairs on the Titanyic.

You would
think. Anyway, I fretted over dependency upon transportation, the
insurance and energy and auto expenses then lucked out to find a job
less than a mile from home, so I ride a bicycle or walk year-around (in
Minnesota!)

You can get semi-dormant insurance with Geico and maybe other
insurers. You park the vehicle for a month and only pay 30% of
insurance. If you need to drive in an emergency you are back to full
cost for that month.


Bret Cahill

 

[Bret Cahill]

The other argument is heavy wheels increase the energy necessary to
get what is basically a flywheel up to speed.

Go to a bike shop and try a really nice $700 racing bicycle. �Compared
to a beach cruiser, when you step down on the pedal it almost leaps
ahead.

Low rolling resistance of HP (80-100 psi) tires makes a world
difference. ďż˝

If you have the rims for it, �refit your mountain bike tires with High
pressure tires.. �You'll be amazed.. �

Tubeless mountain bike tires also make my point. They get rid of
weight where you don't want it.

http://www.maxxis.com/Bicycle/Urban/Hookworm.aspxhttp://www.maxxis.com/Bicycle/Training-Tires/Detonator.aspx

Start with the rear tire.. It carries most of the weight and generates
most of the rolling resistance. ďż˝

Pressure can be even more important than weight.

The pressure in both my tires drops from 80 - 30 over a few weeks, too
slow to notice. I eventually bottom out on a pot hole and pump it
back up so every month or so I rediscover that I really can go several
mph faster.

The reason so many drop cycling are:

10. flat tires

9. nearby high speed vehicle traffic (no bike lane)

8. lack of preparation (no water, etc.)

7. lack of time to get into shape

6. rain or snow

..

..

..


Bret Cahill

 

[john joseph]

tgdenning@earthlink.net wrote:

On Jun 5, 8:17 am, john joseph <nowh...@nowhere.nl> wrote:

READ THIS - in 1994, electric motors accounted for about 25% of the
total use of online electricity in the USA. What are the consequences of
having millions of electric vehicles on the road? More power plants,
more nukes (about time)??? Dunno.

Start with a universal regulation that utilities must buy power from
consumers at a fair rate. There are plenty of commercial buildings
that can take a wind generator or solar panels on the roof, to begin
with. Then put generators of whatever kind along all the highways and
interstates---that way Bret's plan for highway electrification will
have a head start when the politics catches up with him.

With vertical population centers (buildings) having so little land real
estate, it seems unlikely that wind generators are going to take care of
any building, let alone a corporation. It doesn't even work with my
one-story home.

 

[john joseph]

Bret Cahill wrote:

You can get semi-dormant insurance with Geico and maybe other
insurers. You park the vehicle for a month and only pay 30% of
insurance. If you need to drive in an emergency you are back to full
cost for that month.

wtf, that's nutz. I pay $424 a year for auto insurance, full coverage.
That's a little over a dollar-a-day. And I can hardly believe there's a
company that says, "pay as you go part-time".

 

On Jun 5, 7:19 pm, john joseph <nowh...@nowhere.nl> wrote:

tgdenn...@earthlink.net wrote:
On Jun 5, 8:17 am, john joseph <nowh...@nowhere.nl> wrote:
READ THIS - in 1994, electric motors accounted for about 25% of the
total use of online electricity in the USA. What are the consequences of
having millions of electric vehicles on the road? More power plants,
more nukes (about time)??? Dunno.

Start with a universal regulation that utilities must buy power from
consumers at a fair rate. There are plenty of commercial buildings
that can take a wind generator or solar panels on the roof, to begin
with. Then put generators of whatever kind along all the highways and
interstates---that way Bret's plan for highway electrification will
have a head start when the politics catches up with him.

With vertical population centers (buildings) having so little land real
estate, it seems unlikely that wind generators are going to take care of
any building, let alone a corporation. It doesn't even work with my
one-story home.

You asked about *increasing* production for the purpose of fueling
electric cars. Distributed production is one option. If you build some
generating capacity at your house, it will decrease the need for a new
coal-fired plant.

Too bad the entrepreneurial spirit is dying out in the USA.

-tg

 

[Bret Cahill]

READ THIS - in 1994, electric motors accounted for about 25% of the
total use of online electricity in the USA. What are the consequences of
having millions of electric vehicles on the road? More power plants,
more nukes (about time)??? Dunno.

Start with a universal regulation that utilities must buy power from
consumers at a fair rate. There are plenty of commercial buildings
that can take a wind generator or solar panels on the roof, to begin
with. Then put generators of whatever kind along all the highways and
interstates---that way Bret's plan for highway electrification will
have a head start when the politics catches up with him.

With vertical population centers (buildings) having so little land real
estate, it seems unlikely that wind generators are going to take care of
any building, let alone a corporation. It doesn't even work with my
one-story home.

I mentioned the Chicago plan to put wind turbines on buildings in the
windy city to an engineer in the wind dept. at DoE. He said that
would only be a PR stunt as it would only power a floor or two.

You asked about *increasing* production for the purpose of fueling
electric cars. Distributed production is one option. If you build some
generating capacity at your house, it will decrease the need for a new
coal-fired plant.

Before they got rid of him the Walmart CEO had some wacky idea about
putting wind turbines in Walmart parking lots so customers could
charge up as they shopped.

You need only go to a wind farm and see the country side strewn with
blades to know you don't want anyone with access to trial lawyers
under these things.

Last month they closed CA 58 just west of Mojave because of a
"runaway" [free spinning] turbine. They thought that at 90 rpm a
blade would fly off an harpoon a motorist half a mile away on 58.

Too bad the entrepreneurial spirit is dying out in the USA.

www.sunpower.com

 

[Bret Cahill]

You can get semi-dormant insurance with Geico and maybe other
insurers. �You park the vehicle for a month and only pay 30% of
insurance. �If you need to drive in an emergency you are back to full
cost for that month.

wtf, that's nutz. I pay $424 a year for auto insurance, full coverage.
That's a little over a dollar-a-day. And I can hardly believe there's a
company that says, "pay as you go part-time".

I just call them up and say I want to put it into "storage" for a
month. They ask for my mileage and instead of paying $13.30/month I
only pay $4.50/month.

_If_ I can go the full 30 days w/o driving.

If I need the vehicle 27 days later I call them up and they'll ask for
the mileage. They say I can drive but I'll be paying the full $13.30
for that month.

They allow 4 miles / month to idle around the parking lot, keep the
seals from drying out, charge the battery, etc.

Of course, if you get caught driving while in "storage" it's the same
as not having any insurance at all and the vehicle is impounded by the
police.


Bret Cahill

 

On Jun 6, 12:21 pm, Bret Cahill <BretCah...@peoplepc.com> wrote:

READ THIS - in 1994, electric motors accounted for about 25% of the
total use of online electricity in the USA. What are the consequences of
having millions of electric vehicles on the road? More power plants,
more nukes (about time)??? Dunno.

Start with a universal regulation that utilities must buy power from
consumers at a fair rate. There are plenty of commercial buildings
that can take a wind generator or solar panels on the roof, to begin
with. Then put generators of whatever kind along all the highways and
interstates---that way Bret's plan for highway electrification will
have a head start when the politics catches up with him.

With vertical population centers (buildings) having so little land real
estate, it seems unlikely that wind generators are going to take care of
any building, let alone a corporation. It doesn't even work with my
one-story home.

I mentioned the Chicago plan to put wind turbines on buildings in the
windy city to an engineer in the wind dept. at DoE.  He said that
would only be a PR stunt as it would only power a floor or two.

You asked about *increasing* production for the purpose of fueling
electric cars. Distributed production is one option. If you build some
generating capacity at your house, it will decrease the need for a new
coal-fired plant.

Before they got rid of him the Walmart CEO had some wacky idea about
putting wind turbines in Walmart parking lots so customers could
charge up as they shopped.

You need only go to a wind farm and see the country side strewn with
blades to know you don't want anyone with access to trial lawyers
under these things.

Last month they closed CA 58 just west of Mojave because of a
"runaway" [free spinning] turbine.  They thought that at 90 rpm a
blade would fly off an harpoon a motorist half a mile away on 58.

Rooftop turbines have to be framed and caged anyway so that's not a
problem. Walmart roofs are just the place for it, assuming they can
bear the weight and there's enough wind. Remember, the point is to
increase capacity not service the building itself in real time.

-tg

-tg

Too bad the entrepreneurial spirit is dying out in the USA.

www.sunpower.com

 

[Bret Cahill]

READ THIS - in 1994, electric motors accounted for about 25% of the
total use of online electricity in the USA. What are the consequences of
having millions of electric vehicles on the road? More power plants,
more nukes (about time)??? Dunno.

Start with a universal regulation that utilities must buy power from
consumers at a fair rate. There are plenty of commercial buildings
that can take a wind generator or solar panels on the roof, to begin
with. Then put generators of whatever kind along all the highways and
interstates---that way Bret's plan for highway electrification will
have a head start when the politics catches up with him.

With vertical population centers (buildings) having so little land real
estate, it seems unlikely that wind generators are going to take care of
any building, let alone a corporation. It doesn't even work with my
one-story home.

I mentioned the Chicago plan to put wind turbines on buildings in the
windy city to an engineer in the wind dept. at DoE. �He said that
would only be a PR stunt as it would only power a floor or two.

You asked about *increasing* production for the purpose of fueling
electric cars. Distributed production is one option. If you build some
generating capacity at your house, it will decrease the need for a new
coal-fired plant.

Before they got rid of him the Walmart CEO had some wacky idea about
putting wind turbines in Walmart parking lots so customers could
charge up as they shopped.

You need only go to a wind farm and see the country side strewn with
blades to know you don't want anyone with access to trial lawyers
under these things.

Last month they closed CA 58 just west of Mojave because of a
"runaway" [free spinning] turbine. �They thought that at 90 rpm a
blade would fly off an harpoon a motorist half a mile away on 58.

Rooftop turbines have to be framed and caged anyway so that's not a
problem. Walmart roofs are just the place for it, assuming they can
bear the weight and there's enough wind. �Remember, the point is to
increase capacity not service the building itself in real time.

Off the grid romantics, of course, need their "free" energy right next
to their living rooms but it is not yet all that desirable to put wind
farms in every nook and cranny.

Windfarm and solar thermal the desert, PV warehouse roofs, electrify
the freeways and then tell the Pope that Malthus was correct.


Bret Cahill

 

[iman islam]

On Jun 4, 7:58 pm, Bret Cahill <BretCah...@peoplepc.com> wrote:

Check this out, especially the forcing function that increases with
mass.

To keep things simple assume a motor vehicle consists of 2 masses
connected by a spring with const. k and a shock with const c.  Call
the body, frame, engine etc. one mass, m1 and the suspension is the
spring + shock and the wheels are m2.

When there is a forcing function P(t) on m2, which increases linearly
with m2, the equation of motion, derived from summing all the forces
on each mass is:

m1x1''(t) + c(x1'(t) - x2'(t)) + k(x1(t) - x2(t)) = 0

m2x2''(t) + c((x2'(t)-x1'(t)) + k(x2(t) - x1(t)) = m2P(t)

x(t), x'(t) and x"(t) are displacement, velocity and acceleration of
each mass respectively.

Adding both equations:

m1x1''(t) + m2x2''(t) = m2P(t)

or

x1"(t) = [m2P(t) - m2x2"(t)] / m1 = m2 (P(t) - x2"(t)) / m1

x1''(t) is the acceleration on the chassis.

The more you increase m2 [heavy wheels] and decrease m1, the more you
increase x1''(t),  the acceleration on m1.

The short qualitative answer:

The harder you hit the pot hole the harder pothole hits back.
Why duke it out with a pothole?

That's one argument for shifting weight from the wheels to above the
suspension.

The other argument is heavy wheels increase the energy necessary to
get what is basically a flywheel up to speed.

Go to a bike shop and try a really nice $700 racing bicycle.  Compared
to a beach cruiser, when you step down on the pedal it almost leaps
ahead.

Bret Cahill

Understanding Islam
August 30th, 2008
What you are about to read might sound unusual but it could be very
enlightened.


Understanding Islam

by Fr. Theodore Pulcini
Muslims now constitute a significant minority in Western countries,
most notably France, Britain, Germany, Canada, and the United States.
Consequently, those in the West engaged in theological discourse and
pastoral work can no longer consign Islam to the outer limits of their
universe of religious concerns. Islam is no longer just "over there,"
an exotic feature of distant cultures; it is a well-established
component of our own religious landscape and deserves attention from
all who work to further the Reign of God in our culture.

Having taught courses in Islamic civilization as part of the religious
studies curriculum at both secular and church-related institutions, I
can give ample testimony to the antagonistic images of Islam obtaining
in, and actively perpetuated by, many Western circles. In some cases,
it is alarmism that fuels the antagonism ("Muslims are taking over the
world!"); in others, the indignation of post-modern Westerners who
resent the very existence of a powerful religious tradition which
seems to foster "unenlightened" values ("Islam is intolerant, it
oppresses women, etc."). It is a situation fraught with the real
possibility of bigotry and violence.

As "people of religion," we can be particularly effective in shaping
religious sentiment toward Muslims in our society. We can either stoke
the fires of antagonism, feeding into the dominant societal trend of
"demonizing" Islam and Muslims; or we can fight those fires,
challenging people to come to a well-informed, balanced appreciation
of this "other" in our midst. Most of us, I assume, would affirm the
desirability of the latter option. I would like to offer a few
suggestions as to how that option might be realized.

First, expose the caricatures — both our own and those of others. Such
caricatures are usually based on the assumption that Islam is
monolithic and that Muslim communities are homogeneous. Both
assumptions are false. Just as there are many "Christianities," there
are many "Islams" and most have very little to do with "Islamism,"
that militant, extremist fringe of Islam which, despite its claim to
"traditionalism," actually violates such perennial Islamic values as
tolerance, forbearance, hospitality, and broad-mindedness. A number of
excellent resources can help you in this process — see the attached
reading list. All the recommended authors are Christians who have done
much to dispel the rampant misinformation concerning Islam.

Second, reflect on what underlies our tendency to caricature Islam.
Many in the Christian world have thrown themselves headlong into the
process of challenging the traditional shape of our society and want
to eradicate the very memory of its "oppressive" structures. Modernity
is uncomfortable with the demands of tradition. When Islam presents
itself — unabashedly, unashamedly — as a traditional religion, i.e.,
as a religion based on the structures and values of a traditional
cultural system, those who are shaped by secular culture wince. They
are reminded of what our own communities once affirmed (and in some
quarters, still do affirm) to be true and what was once imposed (and
in some quarters, still is imposed) as obligatory. Moreover, I think
many recognize, even if only reluctantly, that in dismantling the
traditional shape of our religious life, in many ways our religious
communities have been debilitated. Islam’s vitality and self-
confidence reminds us of what we have lost. In short, the growing
strength of Islamic identity and the resurgence in Islamic practice
only serve to underscore the progressive weakening of Christian
identity and the steady diminishment of Christian practice in
secularized Western societies. We resent Islam’s newly found vitality
because it draws attention to our present malaise.

Third, appreciate the practical, external expressions of faith that
typify Islamic life. We have much to learn in this regard from Islam.
A few years ago even Pope John Paul II pointed to the Muslim fast
during the month of Ramadan as an example of the kind of zeal and
discipline Christians should, but today rarely do, bring to Lenten
fasting. Islam also requires regular prayer — at least five times a
day for the observant Muslim. (While at the University of Pittsburgh,
I would regularly chance upon a Muslim student in a quiet corner of a
library "making salat" on a prayer rug.) How many Christians can claim
to set aside time for prayer so regularly? Muslims must give alms
(zakat), not just when they feel moved to do so but as a requisite
part of their religious practice; year by year they return a certain
percentage of their wealth to the community to even up the
inequalities that separate the "haves" from the "have nots." Do we
feel so obliged to bridge the gap between the rich and the poor in our
communities? Islamic life requires pilgrimage, an experience now
largely de-emphasized in modern Christian life. It requires bodily
acts of worship like bowing and prostrating, gestures often dismissed
as archaic to the "sophisticated" modern Christian. In short, for all
of our talk of "incarnational" Christianity, we are becoming a
religion less and less likely to enflesh our religious sentiments in
external expression. We stress thought and emotion over physicality,
enforcing a kind of neo-Gnosticism that sees religion primarily as a
"spiritual" sentiment, having little to do with bodily performance.
This is, I would say, a most unfortunate trend. Islam reminds us of
the need for physical religious enactment.

Fourth, highlight the Islamic emphasis on community life and on the
individual’s accountability to community standards. As Christianity in
the Western world becomes more atomized and Christian spirituality
more privatized, Islam provides a strong testimony to the power of
community. One of my Muslim students once remarked, "Wherever I go,
whether in the Islamic world or outside it, even if I cannot find a
local community of Muslims, I am always aware that I am part of a
worldwide community. This is always at the forefront of my mind. It
forges my whole identity. It guides my every action. The umma [Islamic
community] gives me strength, and I willingly give it my loyalty." In
a culture where commitment to religious community is becoming
increasingly rare, and accountability of any sort (whether to a
religious tradition or any other "authority") is seen almost as an
infringement of personal rights, the communocentric emphasis of Islam
can seem somewhat archaic. It should, however, challenge us Christians
in particular to revitalize our communal structures, even if that
means drawing boundaries between ourselves and "the world," boundaries
that have been blurred by encroaching secularization. In re-thinking
our definition of religious communities and re-shaping the dynamics of
life within them, we can learn some valuable lessons from the Muslim
experience.

Fifth, use dialogue with Islam as a way not only to increase our
appreciation of the Islamic tradition but also to deepen our
appreciation of the distinctive features of our own. Make no mistake
about it: despite sizeable areas of "common ground," there is a wide
theological chasm between Islam and Christianity. It was largely in
reaction to an often distorted presentation of Christian doctrine that
Islam formed its own doctrinal heritage. Islamic doctrine challenges
us to embrace anew those facets of Christian theology which
differentiate us from Muslims — especially the mystery of the Trinity
and the divine Sonship of Christ — and then to find new and ever more
insightful ways of articulating these dogmas. Simple repetition of
traditional formulas usually does not suffice to foster greater
understanding of Christianity among Muslims (or among Christians, for
that matter)! In questioning the central Christian doctrines, Islam
serves us well: it requires us to focus specifically on those
distinctive beliefs that are constitutive of our view of God and the
world and to find more effective ways of proclaiming and explaining
them both to those within the "household of Christianity" and to those
without.

Sixth, and finally, make personal contact with Muslim communities and
individuals. It is much more difficult to caricature people we know
than those we keep at a distance. Call the local Islamic center and
ask to be put on the mailing list. These centers often sponsor
lectures of public interest; attend one and talk to members of the
host community. Groups from the mosque and your church may want to
exchange visits. Social service programs can provide opportunities for
mosque and church to join together in a common cause. The
possibilities for such encounters abound and, if realized, usually
bear much good fruit.

Conclusion: On their course evaluation forms, two students in my
"Introduction to Islamic Civilization" wrote remarks that I found
especially gratifying. The first wrote, "When I signed up for this
course, I had nothing but disdain for Muslims; now I am actually able
to see the beauty of their religion." The other wrote, "Studying Islam
has made me better able to see what it means for me to say that I am
Christian." These students articulated well what I consider the two
main reasons for us to come to an appreciation of Islam. Doing so will
enable us not only to affirm this important "other" in our midst and
but also to clarify our own identity.


———————




For more information about Islam

http://english.islamway.com/

http://www.islamhouse.com/

http://www.discoverislam.com/

http://www.islambasics.com/index.php

http://english.islamway.com/

http://www.islamtoday.net/english/

http://www.islamweb.net/ver2/MainPage/indexe.php

http://www.sultan.org/

Contact Us At

Imanway.group@gmail.com

 

[John Fields]

On Thu, 11 Jun 2009 11:13:23 -0700 (PDT), iman islam
<imanway2010@gmail.com> wrote:

On Jun 4, 7:58 pm, Bret Cahill <BretCah...@peoplepc.com> wrote:
Check this out, especially the forcing function that increases with
mass.

To keep things simple assume a motor vehicle consists of 2 masses
connected by a spring with const. k and a shock with const c.  Call
the body, frame, engine etc. one mass, m1 and the suspension is the
spring + shock and the wheels are m2.

When there is a forcing function P(t) on m2, which increases linearly
with m2, the equation of motion, derived from summing all the forces
on each mass is:

m1x1''(t) + c(x1'(t) - x2'(t)) + k(x1(t) - x2(t)) = 0

m2x2''(t) + c((x2'(t)-x1'(t)) + k(x2(t) - x1(t)) = m2P(t)

x(t), x'(t) and x"(t) are displacement, velocity and acceleration of
each mass respectively.

Adding both equations:

m1x1''(t) + m2x2''(t) = m2P(t)

or

x1"(t) = [m2P(t) - m2x2"(t)] / m1 = m2 (P(t) - x2"(t)) / m1

x1''(t) is the acceleration on the chassis.

The more you increase m2 [heavy wheels] and decrease m1, the more you
increase x1''(t),  the acceleration on m1.

The short qualitative answer:

The harder you hit the pot hole the harder pothole hits back.
Why duke it out with a pothole?

That's one argument for shifting weight from the wheels to above the
suspension.

The other argument is heavy wheels increase the energy necessary to
get what is basically a flywheel up to speed.

Go to a bike shop and try a really nice $700 racing bicycle.  Compared
to a beach cruiser, when you step down on the pedal it almost leaps
ahead.

Bret Cahill




Understanding Islam
August 30th, 2008
What you are about to read might sound unusual but it could be very
enlightened.


Understanding Islam

by Fr. Theodore Pulcini
Muslims now constitute a significant minority in Western countries,
most notably France, Britain, Germany, Canada, and the United States.
Consequently, those in the West engaged in theological discourse and
pastoral work can no longer consign Islam to the outer limits of their
universe of religious concerns. Islam is no longer just "over there,"
an exotic feature of distant cultures; it is a well-established
component of our own religious landscape and deserves attention from
all who work to further the Reign of God in our culture.

Having taught courses in Islamic civilization as part of the religious
studies curriculum at both secular and church-related institutions, I
can give ample testimony to the antagonistic images of Islam obtaining
in, and actively perpetuated by, many Western circles. In some cases,
it is alarmism that fuels the antagonism ("Muslims are taking over the
world!"); in others, the indignation of post-modern Westerners who
resent the very existence of a powerful religious tradition which
seems to foster "unenlightened" values ("Islam is intolerant, it
oppresses women, etc."). It is a situation fraught with the real
possibility of bigotry and violence.

As "people of religion," we can be particularly effective in shaping
religious sentiment toward Muslims in our society. We can either stoke
the fires of antagonism, feeding into the dominant societal trend of
"demonizing" Islam and Muslims; or we can fight those fires,
challenging people to come to a well-informed, balanced appreciation
of this "other" in our midst. Most of us, I assume, would affirm the
desirability of the latter option. I would like to offer a few
suggestions as to how that option might be realized.

First, expose the caricatures — both our own and those of others. Such
caricatures are usually based on the assumption that Islam is
monolithic and that Muslim communities are homogeneous. Both
assumptions are false. Just as there are many "Christianities," there
are many "Islams" and most have very little to do with "Islamism,"
that militant, extremist fringe of Islam which, despite its claim to
"traditionalism," actually violates such perennial Islamic values as
tolerance, forbearance, hospitality, and broad-mindedness. A number of
excellent resources can help you in this process — see the attached
reading list. All the recommended authors are Christians who have done
much to dispel the rampant misinformation concerning Islam.

Second, reflect on what underlies our tendency to caricature Islam.
Many in the Christian world have thrown themselves headlong into the
process of challenging the traditional shape of our society and want
to eradicate the very memory of its "oppressive" structures. Modernity
is uncomfortable with the demands of tradition. When Islam presents
itself — unabashedly, unashamedly — as a traditional religion, i.e.,
as a religion based on the structures and values of a traditional
cultural system, those who are shaped by secular culture wince. They
are reminded of what our own communities once affirmed (and in some
quarters, still do affirm) to be true and what was once imposed (and
in some quarters, still is imposed) as obligatory. Moreover, I think
many recognize, even if only reluctantly, that in dismantling the
traditional shape of our religious life, in many ways our religious
communities have been debilitated. Islam’s vitality and self-
confidence reminds us of what we have lost. In short, the growing
strength of Islamic identity and the resurgence in Islamic practice
only serve to underscore the progressive weakening of Christian
identity and the steady diminishment of Christian practice in
secularized Western societies. We resent Islam’s newly found vitality
because it draws attention to our present malaise.

Third, appreciate the practical, external expressions of faith that
typify Islamic life. We have much to learn in this regard from Islam.
A few years ago even Pope John Paul II pointed to the Muslim fast
during the month of Ramadan as an example of the kind of zeal and
discipline Christians should, but today rarely do, bring to Lenten
fasting. Islam also requires regular prayer — at least five times a
day for the observant Muslim. (While at the University of Pittsburgh,
I would regularly chance upon a Muslim student in a quiet corner of a
library "making salat" on a prayer rug.) How many Christians can claim
to set aside time for prayer so regularly? Muslims must give alms
(zakat), not just when they feel moved to do so but as a requisite
part of their religious practice; year by year they return a certain
percentage of their wealth to the community to even up the
inequalities that separate the "haves" from the "have nots." Do we
feel so obliged to bridge the gap between the rich and the poor in our
communities? Islamic life requires pilgrimage, an experience now
largely de-emphasized in modern Christian life. It requires bodily
acts of worship like bowing and prostrating, gestures often dismissed
as archaic to the "sophisticated" modern Christian. In short, for all
of our talk of "incarnational" Christianity, we are becoming a
religion less and less likely to enflesh our religious sentiments in
external expression. We stress thought and emotion over physicality,
enforcing a kind of neo-Gnosticism that sees religion primarily as a
"spiritual" sentiment, having little to do with bodily performance.
This is, I would say, a most unfortunate trend. Islam reminds us of
the need for physical religious enactment.

Fourth, highlight the Islamic emphasis on community life and on the
individual’s accountability to community standards. As Christianity in
the Western world becomes more atomized and Christian spirituality
more privatized, Islam provides a strong testimony to the power of
community. One of my Muslim students once remarked, "Wherever I go,
whether in the Islamic world or outside it, even if I cannot find a
local community of Muslims, I am always aware that I am part of a
worldwide community. This is always at the forefront of my mind. It
forges my whole identity. It guides my every action. The umma [Islamic
community] gives me strength, and I willingly give it my loyalty." In
a culture where commitment to religious community is becoming
increasingly rare, and accountability of any sort (whether to a
religious tradition or any other "authority") is seen almost as an
infringement of personal rights, the communocentric emphasis of Islam
can seem somewhat archaic. It should, however, challenge us Christians
in particular to revitalize our communal structures, even if that
means drawing boundaries between ourselves and "the world," boundaries
that have been blurred by encroaching secularization. In re-thinking
our definition of religious communities and re-shaping the dynamics of
life within them, we can learn some valuable lessons from the Muslim
experience.

Fifth, use dialogue with Islam as a way not only to increase our
appreciation of the Islamic tradition but also to deepen our
appreciation of the distinctive features of our own. Make no mistake
about it: despite sizeable areas of "common ground," there is a wide
theological chasm between Islam and Christianity. It was largely in
reaction to an often distorted presentation of Christian doctrine that
Islam formed its own doctrinal heritage. Islamic doctrine challenges
us to embrace anew those facets of Christian theology which
differentiate us from Muslims — especially the mystery of the Trinity
and the divine Sonship of Christ — and then to find new and ever more
insightful ways of articulating these dogmas. Simple repetition of
traditional formulas usually does not suffice to foster greater
understanding of Christianity among Muslims (or among Christians, for
that matter)! In questioning the central Christian doctrines, Islam
serves us well: it requires us to focus specifically on those
distinctive beliefs that are constitutive of our view of God and the
world and to find more effective ways of proclaiming and explaining
them both to those within the "household of Christianity" and to those
without.

Sixth, and finally, make personal contact with Muslim communities and
individuals. It is much more difficult to caricature people we know
than those we keep at a distance. Call the local Islamic center and
ask to be put on the mailing list. These centers often sponsor
lectures of public interest; attend one and talk to members of the
host community. Groups from the mosque and your church may want to
exchange visits. Social service programs can provide opportunities for
mosque and church to join together in a common cause. The
possibilities for such encounters abound and, if realized, usually
bear much good fruit.

Conclusion: On their course evaluation forms, two students in my
"Introduction to Islamic Civilization" wrote remarks that I found
especially gratifying. The first wrote, "When I signed up for this
course, I had nothing but disdain for Muslims; now I am actually able
to see the beauty of their religion." The other wrote, "Studying Islam
has made me better able to see what it means for me to say that I am
Christian." These students articulated well what I consider the two
main reasons for us to come to an appreciation of Islam. Doing so will
enable us not only to affirm this important "other" in our midst and
but also to clarify our own identity.


———————




For more information about Islam

http://english.islamway.com/

http://www.islamhouse.com/

http://www.discoverislam.com/

http://www.islambasics.com/index.php

http://english.islamway.com/

http://www.islamtoday.net/english/

http://www.islamweb.net/ver2/MainPage/indexe.php

http://www.sultan.org/

Contact Us At

Imanway.group@gmail.com

---
Interesting...

Islam is supposed to be about honesty and yet you tout it by luring the
unsuspecting into reading your post by lying about the subject of your
post.

Is that permitted by the Koran?


JF