Go Back   EcoModder Forum > EcoModding > EcoModding Central
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 04-10-2018, 02:06 PM   #21 (permalink)
Master EcoWalker
 
RedDevil's Avatar
 
Join Date: Dec 2012
Location: Nieuwegein, the Netherlands
Posts: 3,998

Red Devil - '11 Honda Insight Elegance
Team Honda
90 day: 47.72 mpg (US)
Thanks: 1,711
Thanked 2,245 Times in 1,454 Posts
Inertia The energy contained in a moving or rotating body is not linear but quadratic to speed.
It takes 0.5 Joule to speed up that kilogram to 1 meter per second, it takes 2 Joule for 2 m/s, 4.5 for 3 m/s, etc.
Inertia if you mean the contained energy in your formula is not mass * radius but just mass * (radius ^ 2) / 2.

And remember, only the speed matters, not the direction; whether it is straight, turning slowly in a big circle or fast in a tiny circle is indifferent. Only its speed matters.

__________________
2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gmeter or 0.13 Mmile.


For confirmation go to people just like you.
For education go to people unlike yourself.

Last edited by RedDevil; 04-10-2018 at 05:43 PM..
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 04-10-2018, 03:06 PM   #22 (permalink)
EcoModding Apprentice
 
Join Date: Oct 2010
Location: ireland
Posts: 102
Thanks: 8
Thanked 52 Times in 34 Posts
Quote:
Originally Posted by RedDevil View Post
Inertia is not linear but quadratic to speed.
It takes 0.5 Joule to speed up that kilogram to 1 meter per second, it takes 2 Joule for 2 m/s, 4.5 for 3 m/s, etc.
Inertia, if you mean the contained energy, in your formula is not mass * radius but mass * (radius ^ 2) / 2.

And remember, only the speed matters, not the direction; whether it is straight, turning slowly in a big circle or fast in a tiny circle is indifferent. Only its speed matters.
You appear to be confusing the term "inertia" with "kinetic energy".

A mass M moving at a velocity V has a kinetic energy of 0.5 * M * V * V.

This however is not inertia.

Inertia is a measure of a body's resistance to changes in velocity.

It can be found from Newton's second law F = M * A and thus M = F / A

As there is no gravity in space, astronauts determine their mass (inertia) in a special device that applies a force and the rate of acceleration is measured. The rearranged Newtons 2nd equation is then used to calculate their mass (inertia).
  Reply With Quote
The Following User Says Thank You to cr45 For This Useful Post:
RedDevil (04-10-2018)
Old 04-10-2018, 04:36 PM   #23 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,561
Thanks: 7,736
Thanked 8,554 Times in 7,041 Posts
Quote:
What are some of the best tire setups you have tried and also best mileage increaser. I know the biggest difference comes from driving habits. I am just curios to see what mods helped most too.
The received wisdom in the air-cooled VW world is to downsize the fronts. Keep the 165-15 in back for traction, and go to 135- or 145-15 in front. And put the nose on the ground.

Something closer to your front-wheel drive platform is the Rabbit pickups I've seen at the drag races. They run short, wide tires in front and tall, narrow tires in back. Maybe 14s and 16s?

Agree with CapriRacer at Permalink #7. Settle on the tire and then pick the wheel; and it's width (affects sidewall stiffness and turn-in).
__________________
.
.
Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster

____________________
  Reply With Quote
Old 04-10-2018, 05:39 PM   #24 (permalink)
Master EcoWalker
 
RedDevil's Avatar
 
Join Date: Dec 2012
Location: Nieuwegein, the Netherlands
Posts: 3,998

Red Devil - '11 Honda Insight Elegance
Team Honda
90 day: 47.72 mpg (US)
Thanks: 1,711
Thanked 2,245 Times in 1,454 Posts
Quote:
Originally Posted by cr45 View Post
You appear to be confusing the term "inertia" with "kinetic energy".

A mass M moving at a velocity V has a kinetic energy of 0.5 * M * V * V.

This however is not inertia.

Inertia is a measure of a body's resistance to changes in velocity.

It can be found from Newton's second law F = M * A and thus M = F / A

As there is no gravity in space, astronauts determine their mass (inertia) in a special device that applies a force and the rate of acceleration is measured. The rearranged Newtons 2nd equation is then used to calculate their mass (inertia).
You are right. Inertia is mass (resistance to change speed), and rotational inertia is resistance to change rotational motion.
A bigger wheel has way bigger rotational inertia, but it covers a much larger distance than a smaller wheel rotating bat the same speed.

In the end what matters is how fast the thread moves - that's the same as the speed of the car, regardless of the size of the wheels.
__________________
2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gmeter or 0.13 Mmile.


For confirmation go to people just like you.
For education go to people unlike yourself.
  Reply With Quote
Old 04-11-2018, 07:56 AM   #25 (permalink)
Master EcoModder
 
Joggernot's Avatar
 
Join Date: Jun 2013
Location: Texas
Posts: 449
Thanks: 1,748
Thanked 126 Times in 105 Posts
Quote:
Originally Posted by RedDevil View Post
You are right. [URL="https://en.wikipedia.org/wiki/Inertia"]...
In the end what matters is how fast the thread moves - that's the same as the speed of the car, regardless of the size of the wheels.
Well, my tires are in contact with the ground. When in contact with the ground the tread has zero forward motion. The car is still going 45 mph. The only thing on a wheel that is going the speed of the car is the axle. The top of the tire is going twice the speed of the car or 90 mph. Or is my thinkin' stinkin'...?
  Reply With Quote
Old 04-11-2018, 08:42 AM   #26 (permalink)
Master EcoModder
 
Join Date: May 2012
Location: Tampa, FL
Posts: 1,745

Volt, gas only - '12 Chevrolet Volt Premium
90 day: 38.02 mpg (US)

Volt, electric only - '12 Chevrolet Volt Premium
90 day: 132.26 mpg (US)

Yukon Denali Hybrid - '12 GMC Yukon Denali Hybrid
90 day: 21.48 mpg (US)
Thanks: 206
Thanked 420 Times in 302 Posts
Quote:
Originally Posted by Joggernot View Post
Well, my tires are in contact with the ground. When in contact with the ground the tread has zero forward motion. The car is still going 45 mph. The only thing on a wheel that is going the speed of the car is the axle. The top of the tire is going twice the speed of the car or 90 mph. Or is my thinkin' stinkin'...?
I believe this is once again where a discussion spins off about linear and angular velocity.
__________________




  Reply With Quote
Old 04-11-2018, 09:22 AM   #27 (permalink)
Tire Geek
 
CapriRacer's Avatar
 
Join Date: May 2008
Location: Let's just say I'm in the US
Posts: 794
Thanks: 4
Thanked 388 Times in 237 Posts
I strongly suspect that the rotating mass of the tire causes an insignificant affect on fuel economy - that even a significantly wider tire barely changes the actual fuel consumption. I suspect this because the car manufacturers continue to go to wider and wider tires.
__________________
CapriRacer

Visit my website: www.BarrysTireTech.com
New Content every month!
  Reply With Quote
Old 04-11-2018, 09:28 AM   #28 (permalink)
Master EcoModder
 
Ecky's Avatar
 
Join Date: Dec 2011
Location: New Zealand
Posts: 5,005

ND Miata - '15 Mazda MX-5 Special Package
90 day: 42.54 mpg (US)
Thanks: 2,866
Thanked 2,501 Times in 1,547 Posts
Ahh, the march of progress.

Admittedly you get two more doors and it holds the brakes for you so you don't roll backward in neutral.

  Reply With Quote
The Following User Says Thank You to Ecky For This Useful Post:
Gasoline Fumes (04-11-2018)
Old 04-11-2018, 12:10 PM   #29 (permalink)
Master EcoWalker
 
RedDevil's Avatar
 
Join Date: Dec 2012
Location: Nieuwegein, the Netherlands
Posts: 3,998

Red Devil - '11 Honda Insight Elegance
Team Honda
90 day: 47.72 mpg (US)
Thanks: 1,711
Thanked 2,245 Times in 1,454 Posts
Quote:
Originally Posted by Joggernot View Post
Well, my tires are in contact with the ground. When in contact with the ground the tread has zero forward motion. The car is still going 45 mph. The only thing on a wheel that is going the speed of the car is the axle. The top of the tire is going twice the speed of the car or 90 mph. Or is my thinkin' stinkin'...?
On average every part of your wheels is moving forward at the same speed as the rest of your car. So the forward motion part of inertia is equal to fixed parts of the same mass.
Then it also takes energy to spin up the wheel; slightly less than the forward motion requires. The total inertia is the sum of both; slightly less than twice the mass of the wheel.
__________________
2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gmeter or 0.13 Mmile.


For confirmation go to people just like you.
For education go to people unlike yourself.
  Reply With Quote
Old 04-11-2018, 12:53 PM   #30 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,561
Thanks: 7,736
Thanked 8,554 Times in 7,041 Posts
Quote:
Originally Posted by Ecky
Ahh, the march of progress.
Similarly, over it's production run, the Beetle went from 25hp/40mpg to 50hp/28mpg.

__________________
.
.
Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster

____________________
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com