Stupid Physics Question

[Jimrpa]

If I borrow my friend’s ICE Escape, fill the tank, weigh the vehicle, drive it until the vehicle stops running (I.e., is out of gas), then weigh it again, the vehicle will weigh a bit less. Specifically, it will weigh one tank full of gas less, or whatever about 15 gallons of gas weighs. (Anyone know where I’m going? ?)
If I fully charge my Mustang Mach E, weigh I, then drive it until it stops (I.e., drain the HVB), then weigh the car again, what will the difference in weight be?
What’s going on here?

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[Kamuelaflyer]

If I borrow my friend’s ICE Escape, fill the tank, weigh the vehicle, drive it until the vehicle stops running (I.e., is out of gas), then weigh it again, the vehicle will weigh a bit less. Specifically, it will weigh one tank full of gas less, or whatever about 15 gallons of gas weighs. (Anyone know where I’m going? ?)
If I fully charge my Mustang Mach E, weigh I, then drive it until it stops (I.e., drain the HVB), then weigh the car again, what will the difference in weight be?
What’s going on here?

This is a funny way to ask about the remote Frunk release on 2021 Job 1’s.

 

[DomiinUS]

it will be a little bit less heavy....
but - it is like an elephant with or without a fly on top (the difference is really hard to measure)
The reason for the difference in weight is E = m *c^2

 

[ctenidae]

In case it is a serious question, the ICE would weigh a little over 100 pounds less.
With a drained battery, the MME will weigh somewhere between 8,600 and 26,000 pounds more.

It really depends on what kind of tow truck has come to get it. Either way, your ice cream is going to melt in the frunk.

 

[Jimrpa]

it will be a little bit less heavy....
but - it is like an elephant with or without a fly on top (the difference is really hard to measure)
The reason for the difference in weight is E = m *c^2

Right. I was going in that direction BUT a friend of mine keeps insisting that gasoline is the most efficient way to store energy (short of leveraging nuclear bonds). He references the energy density per kilogram. So, I’m trying to rationalize the amount of energy required to move a certain distance (I’m going to simplify the problem by saying both vehicles are using the same amount of energy and moving equal distances - yes, I know those are incorrect assumptions, but order of magnitude, they will work for this problem).

 

[Jimrpa]

In case it is a serious question, the ICE would way a little over 100 pounds less.
With a drained battery, the MME will weigh somewhere between 8,600 and 26,000 more.

It really depends on what kind of tow truck has come to get it. Either way, your ice cream is going to melt in the frunk.

Yes, this is a serious question.

 

[Scooby24]

Preface: Not an expert;just my understanding:

gasoline is incredibly inefficient. There are many many byproducts of the energy obtained from fuel in the form of waste and conversion. There is a whole lot of energy density per kilo but because it's so inefficient, much of that energy is lost.

energy stored in a battery is much more efficient and has very little byproducts. It's less energy dense so it has much less mass.

 

[ctenidae]

I had to do the math - a 91 kwh battery has about 3.267x10^-9 kg of electrons in it. That's 0.000000003267 kg, or 7.2x10^-9 ounces.

Theoretically, if you were running as much juice through it as you could, you might be able to get half that out of the battery and into the circuit, but the electrons will still be in the car, so the weight doesn't go anywhere.

Your ice cream is still soup, though. And it's starting to smell.

 

[Jimrpa]

In case it is a serious question, the ICE would way a little over 100 pounds less.
With a drained battery, the MME will weigh somewhere between 8,600 and 26,000 more.

It really depends on what kind of tow truck has come to get it. Either way, your ice cream is going to melt in the frunk.

Oh, and we are assuming the koi pond in the frunk is not disturbed and the bubbler is powered independently ?

 

[bruceski88]

it will be a little bit less heavy....
but - it is like an elephant with or without a fly on top (the difference is really hard to measure)
The reason for the difference in weight is E = m *c^2

Yeah. c^2 is 9x 10^16. so less than a fly

 

[Jimrpa]

I do appreciate the answers. Can’t wait to go back to my friend (who’s a bit of a “Sheldon”, except lacking several of the PhDs) ?

 

[ctenidae]

BUT a friend of mine keeps insisting that gasoline is the most efficient way to store energy (short of leveraging nuclear bonds). He references the energy density per kilogram.

Your friend is right, to a point. Gasoline is about 100 times as energy dense as a Li-ion battery. But, a gas engine is only about 15-20% efficient(meaning 80% gets turned into heat and blown out into the atmosphere). An EV is 60-80% efficient, so it starts to balance out pretty quickly.

Most of the time, when someone is arguing in favor of ICE, they are very very selective in the attributes they consider, making it very difficult to have an effective conversation.

 

[CompilerBreak]

Right. I was going in that direction BUT a friend of mine keeps insisting that gasoline is the most efficient way to store energy (short of leveraging nuclear bonds). He references the energy density per kilogram. So, I’m trying to rationalize the amount of energy required to move a certain distance (I’m going to simplify the problem by saying both vehicles are using the same amount of energy and moving equal distances - yes, I know those are incorrect assumptions, but order of magnitude, they will work for this problem).

Energy density - Energy density - Wikipedia Yes there's a difference, but that's hardly an argument against electric cars, we can generate new electricity easily (wind, solar, hydro), but gas we just consume, it'll run out eventually and then you're stuck with crappy ethanol.

Plus, if they're really about density, they should be on the hydrogen fuel cell bandwagon

 

[ctenidae]

Oh, and we are assuming the koi pond in the frunk is not disturbed and the bubbler is powered independently ?

Well, that changes things. We're going to have to get into some serious Bistromathics for this. Anyone know a good Italian restaurant?

 

[Maquis]

The battery in your ER contains approximately the same energy as 2.7 gallons of gasoline. You can drive your car 270 miles on that energy. He can go maybe 100 miles in his ICE on 2.7 gallons.

So which is more efficient?

His advantage is that he can easily store more than 2.7 gallons of gasoline, but storage density does not equate to efficiency.

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