Realcent.org

I drive a Ford Focus hatchback. The Focus is front wheel drive. I put my coins in the the back during pickups and dumps. (Currently about $5000 in dimes). While driving I can feel this extra weight effect the handling. (The steering feels looser). I can only attribute this looser feeling in the steering to the added weight in the back lifting weight off of the front wheels and thus making the front wheels less in contact with the road surface both in terms of tire surface area connected to the road and pounds per square inch pushing down on the tires. If the drive wheels have less weight bearing down on them it seems to reason that they would be experiencing less friction and less rolling resistance. Likewise the back wheels don't serve any function in the transfer of power through the power train and to the roadway. The back tires do however experience friction and rolling resistance and, with the added weight it should stand to reason that these factors would increase on the back tires. My question to the members of the forum is what effect on gas mileage will this have? Expecially over the course of say 1000 miles of interstate driving? Will mileage be a net gain or negative?

Net negative. Does not matter where the weight is. Extra pounds moved requires extra energey used = extra full burned.

yep definately negative

Pump those back tires up right full of air. That should help. Less rubber in contact with the road. I also agree with the others, more weight=less mileage. Sort and dump those before you get home to save gas!

Rodebaugh wrote:Net negative. Does not matter where the weight is. Extra pounds moved requires extra energey used = extra full burned.

Maybe not extra fuel burned.

If your pickup bank is uphill from your house and your dump bank is downhill.

Assuming friction is negligible.

Potential energy will be spent by your bank.

U=mgh

Thogey wrote:

Rodebaugh wrote:Net negative. Does not matter where the weight is. Extra pounds moved requires extra energey used = extra full burned.

Maybe not extra fuel burned.

If your pickup bank is uphill from your house and your dump bank is downhill.

Assuming friction is negligible.

Potential energy will be spent by your bank.

U=mgh

This is true. Just need a uphill pickup and downhill dump loctaed in a vacuum with no gravity. Sounds like this could work in California.

Rodebaugh wrote:Net negative. Does not matter where the weight is. Extra pounds moved requires extra energey used = extra full burned.

That's what I thought also. I just wanted to hear what others thought. The one factor that I thought might make a difference was that once I got on the interstate and got up to speed, I would only need to maintain that speed. This would require less engery than speeding up and slowing down and starting and stopping.

Rodebaugh wrote:

Thogey wrote:

Rodebaugh wrote:Net negative. Does not matter where the weight is. Extra pounds moved requires extra energey used = extra full burned.

Maybe not extra fuel burned.

If your pickup bank is uphill from your house and your dump bank is downhill.

Assuming friction is negligible.

Potential energy will be spent by your bank.

U=mgh

This is true. Just need a uphill pickup and downhill dump loctaed in a vacuum with no gravity. Sounds like this could work in California.

Friction would be confined to the wheel bearings. The angular momentum created by the wheels turning would make that force negligible.

Gravity is OK as it is a component of PE (U) (paid for by the bank). Unless the vehicle is going to travel fast enough to reach terminal velicity (vs air friction) an airless environment (vacume) is not necessary.

Since the mass of your vehicle actually increases at the uphill source bank, your potential energy will increase at the pickup (paid for by the source). Gravity will convert the PE to KE=1/2*MV^2.

An uphill source will save you gas..

Uphill source and downhill dump=no problem

I once read each 50 pounds you will loose 1/2 mpg efficiency. This probably differs by vehicle to some degree.

F=ma

When you increase the mass of an object it takes more force to accelerate it.

Once an object of mass is moving it has more energy than an object of less mass and will require more force to create 'negative' acceleration (reduction of velocity or slow it down).

1/2 mpg would depend on the constants involved or the mechanics of a particular vehicle.

Thogey wrote:Friction would be confined to the wheel bearings. The angular momentum created by the wheels turning would make that force negligible.
Gravity is OK as it is a component of PE (U) (paid for by the bank). Unless the vehicle is going to travel fast enough to reach terminal velicity (vs air friction) an airless environment (vacume) is not necessary.
Since the mass of your vehicle actually increases at the uphill source bank, your potential energy will increase at the pickup (paid for by the source). Gravity will convert the PE to KE=1/2*MV^2.
An uphill source will save you gas..
Uphill source and downhill dump=no problem

Friction is envoled in everything from the tires touching the road to the exhast running out the tailpipe. Lubes lesson it.....but its still there.

Air causes friction at all times. An object needs not even be in motion for it to be there.....it may not be in action but its there. Terminal velocity is only a point. A point at which friction reaches a level so great that no further veleocity may be obtained by a falling objcect have you......but still just a point.

thedrifter wrote:. My question to the members of the forum is what effect on gas mileage will this have? Expecially over the course of say 1000 miles of interstate driving?

You need a closer bank

Silver Addict wrote:

thedrifter wrote:. My question to the members of the forum is what effect on gas mileage will this have? Expecially over the course of say 1000 miles of interstate driving?

You need a closer bank

I admit I was impressed with the physics refresher, but SA nailed it here.

Rodebaugh wrote:

Thogey wrote:Friction would be confined to the wheel bearings. The angular momentum created by the wheels turning would make that force negligible.
Gravity is OK as it is a component of PE (U) (paid for by the bank). Unless the vehicle is going to travel fast enough to reach terminal velicity (vs air friction) an airless environment (vacume) is not necessary.
Since the mass of your vehicle actually increases at the uphill source bank, your potential energy will increase at the pickup (paid for by the source). Gravity will convert the PE to KE=1/2*MV^2.
An uphill source will save you gas..
Uphill source and downhill dump=no problem

Friction is envoled in everything from the tires touching the road to the exhast running out the tailpipe. Lubes lesson it.....but its still there.

Air causes friction at all times. An object needs not even be in motion for it to be there.....it may not be in action but its there. Terminal velocity is only a point. A point at which friction reaches a level so great that no further velocity may be obtained by a falling object have you......but still just a point.

Doc you would argue with a brick wall

I know what terminal velocity is: drag=gravity

for the purposes of this discussion Friction and drag would be negligable at road speeds.

I'm not saying those forces friction and drag don't exist.I'm just saying a downhill ride would be cheaper with greater with vehicle of greater mass. Because you would start with greater potential energy.

Now admit I'm right just break down and admit it.

Pump those back tires up right full of air. That should help. Less rubber in contact with the road. I also agree with the others, more weight=less mileage. Sort and dump those before you get home to save gas!

Yes, keeping tires properly inflated will increase gas mileage. In summer, I keep my tires closer to maximum inflation. However, on a rainy or winter day when the roads might be slick, this would decrease traction, making steering and stopping more difficult. So I lower my tire pressure to 28 lbs which is normal for my vehicle. To find out your proper tire inflation, open the drivers door. There should be sticker which indicates proper tire inflation. Once, I was stuck on ice, slopping towards a lake and unable to move forward. I dropped the tire pressure on my front tires (I also have front wheel drive) to 14 lbs. I drove away, as though I had chains. Once I got up the hill and on better roads, I stopped and increased the tire pressure to 28 lbs. That saved me hours waiting for road service.

keeping tires properly inflated will increase gas mileage. That is what candidate obumer said in 2008. WOW! WHAT A SMART GUY!

Thogey is right.

Never thought I would say this.. but "Sort less"

That is a lot of dimes. Usually the silver percentage on dimes (present company excluded) would not cover you transporting them very far. The kinetic energy when you get that load up to speed should allow you to make a bigger dent in whatever you plow into.. but that load shifting forward after you are pinned behind the airbag could be deleterious to your health.

Aqualung my friend, did you start away uneasy? Was there ice clinging on your beard? You must have been in agony!

Ill be here all week..

I don't like to be disagreeable, but in my opinion moving some of the weight forward would increase your gas mileage. Here's why:

With all the weight in the back, the front of the car is raised. This allows increased wind resistance under the car. Even if the car is raised at just 1 degree from the horizontal, as you increase speed there will be a resulting increase of a horizontal force vector pushing in the opposite direction of your travel. The amount of savings will be neglible but there will be some. The physics here is simple.

Buy a bicycle

Diggin4copper wrote:Aqualung my friend, did you start away uneasy? Was there ice clinging on your beard? You must have been in agony!

Snot running down his nose greasy fingers smearing shabby clothes.

TwoAndAHalfCents wrote:

Diggin4copper wrote:Aqualung my friend, did you start away uneasy? Was there ice clinging on your beard? You must have been in agony!

Snot running down his nose greasy fingers smearing shabby clothes.

And you catch your raffling last breath with deep sea diver sounds.

I don't understand the Jethro Tull references? I like the band and the song, but???