I did the math once and determined that the effort of leaning over to pick up a lost penny pays less than minimum wage. Now. I make it harder. If you have a penny in you car, does the drag that its mass creates offset the price of gas used to carry the penny.
I would question the first calculation. If we allow five seconds for a leisurely penny-picking maneuver, that’s .12 a minute or $7.20/hr. That is better than minimum wage for much of the US. Since five seconds seems overly generous to me, I’d think you could speed things up enough to make minimum wage anywhere in the US.
I’ll let someone else try to address the second question, but I think we’re going to need clarification: for how long are we carrying this penny? The answer will be different if we’re taking it home from the store vs hauling it across the country.
Wait, people are getting paid to pick up pennies? Because that’s what the OP is saying. Pausing your stroll to pick one up doesn’t “pay” anything. Picking one up increases your net worth, increases your cardio workout and increases your flexibility. All on time that you are already getting paid for(if at work) or otherwise wouldn’t pay you a cent (if not at work.) Win-win.
I drive about 5,000 miles a year, but I don’t see how much I drive matters. Where I drive affects the gas price piece, and for the diligent I’m in south Georgia. Are you saying that over time the pennies could increase their mass? (joke) No, I know that you mean I have to calculate the car and all of that. I’m not looking for that specific of a number. I have probably 30 pennies in my car. Should I throw them out the window?
I’m going to go out on a limb and say no, the penny’s mass (for any reasonable commute) does not use up a penny of gas.
Fuel use comes from the effects:
(1) Overcoming air resistance.
(2) Overcoming road friction
(3) Starting and stopping the car at lights.
Since the penny is being held inside the car, it doesn’t affect the aerodynamics of the car, so (1) has no effect.
The effect of (2) can be modeled by having gas usage during the being proportional to the weight of the car, which is affected slightly by the additional weight of the penny. (And the cost of that gas is of course directly proportional to the amount of gas.) But even if your commute uses $100 worth of gas, and we attribute all of that gas usage to ground friction, a small car weighs 1000000g, while a penny weighs 2.5g, so we’d expect the incremental cost due to the penny to have the same ratio, so transporting the penny costs some small fraction of a cent.
I’d argue (with more hand waving) that (3) is the same way. Gas usage is proportional to mass, mass off the penny is a trivial fraction of the car’s weight, so unless you’re using unrealistic amounts of gas already, the incremental cost of the penny is far less than a cent.
You did not calculate in the future medical costs on my spine for bending over to pick up the penny. hehehe
The mass of the pennies is definitely affecting your mileage. But I don’t think it would be measurable until you had at least a couple of pounds of them. So don’t throw them away - spend them. Swap their mass for the mass of a granola bar.
No he means that the mass of the penny will cause a constant addition to the mass of the car and therefore a roughly constant increase in the amount of gas you have to use per mile driven. Therefore if you drive far enough with the penny in the car eventually the cost of moving the penny will exceed 1 cent. This may be of course farther than the car could drive in its lifetime and almost certainly is.
To answer your other question, no don’t throw them out the window, take them home and put them wherever you put your loose change.
And the question really seems to be is something like “What is the difference between the average MPG of a car carrying one penny minus the MPG without it?” That is, if you were already going to drive a piece (regardless of penny possession), how much more would it cost to take that penny along for the ride?
Also, the answer may be curved depending on how many pennies you have, so it’s possible that 100 pennies gives you a lower Cost Per Penny than just one.
Thanks Dracoi.
That’s a weird curve. I would think there’s a linear answer. But thanks to all of you. I know where to turn when I have a weird question rattling around in my head.
Yeah, I was thinking that the goal was “driving the penny home to put in your change jar”, but now that I re-read the OP, that’s not clear…
I don’t think so, if you mean incremental cost per penny on a trip you were already going to make. If you’re making a 100km commute just to pick up the penny, all bets are off.
My point was that things that effect gas usage in cars are neatly divided into two categories: Things like air resistance that extra mass has no effect on so additional pennies are “free”, and things like rolling resistance and accelerating that are proportional to mass, so additional pennies make a uniform contribution (although one ridiculously smaller than that of the car itself).
Silenus, yes you are paid to pick up a penny $.01. But that’s not even my question.
No I mean just having the penny in your car, lets say for 6 months.
Yeah I mean the marginal (incremental) cost.
It’s time for merry math. A post-1982 U.S. penny wieghs 2.5 grams or 167 per pound.
A 2012 Honda Accord has a curb weight of 3216 pounds, and a combined city and highway mileage of 27 mpg. That means a Honda weighs as much as 537,072 pennies.
Gasoline is about 6 pounds per gallon, which works out to about .22 pounds per mile. Therefore, it takes 0.037037 gallons/.22 pounds to carry 3216 pounds for one mile.
Assume gas is $3.50 per gallon. the cost of gas needed to travel one mile is 12.96295 – let’s say 13 cents. That means 13 cents of gas can carry 537,072 pennies for one mile. The addition or subtraction of a single penny to the weight of a car causes only an inifinitesimal change in the cost of fuel.
I’d say we should be able to calculate the extra gas for carrying a penny. If anyone out there drives a semi, it should be easy to say that an empty trailer gives them x mpg while a trailer with a 3-ton load gives them y mpg. Since the trailer and rig have the same aerodynamics, the only difference is due to weight. Then we could figure out the percentage of the load represented by a penny and multiply it by the change in mpg.
But, again, we’d need to know distance to get a cost because we have to multiply mpg by miles to get gallons.
I can’t find a good cite for difference in fuel, but I see WikiAnswers has someone who guesses 6-7 mpg loaded and 8 mpg empty. Let’s say 6 mpg is fully loaded at 80,000 lbs (the maximum in the US). A modern penny is about 180 to the pound. So fully loaded is 14.4 million pennies, for a reduction of 2 mpg.
Each penny is about 1.4x10-7 mpg. At $4/gal for fuel (that’s high, obviously), we’re only paying $5.6x10-7 per penny-mile. So you would need to drive 18,000 miles before the penny was worth less than the fuel to transport it.
Clearly the weak point in the calculations is the mpg for the truck, but it looks to me like pennies are worth a lot more than the OP thinks. 
100lbs of extra weight costs you 2% efficiency. From here.
You drive 20k miles per year, at 20mpg, that’s 1000 gallons of gas per year. 2% efficiency loss is 20 gallons/yr or $60 ($3 per gallon of gas).
So 100lbs costs $60 per year.
There are roughly 200 pennies per pound, so that’s $200 of pennies costing $60 per year.
In order for those $200 of pennies to cost you $200 of additional gas, (penny for penny) you would have to drive for 3.3 years, or 67,000 miles.