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How much additional weight would the water have added to the bus and how much strength would be needed to lift the bus out of the water in the way that he did?

user31418
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3 Answers3

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Lifting a bus full of water is one thing, as the other answers have covered in detail. However, Clark is instead pushing a submerged bus out of a lake. The fact that it's underwater actually makes it lighter due to buoyancy. Steel weighs 7.6 g/cm^3, but it's displacing water which weighs 1 g/cm^3. Assuming nearly all of the weight of the bus is from steel, Clark only has to move about 87% of the on-land weight of the bus while it's submerged. Accounting for the less-dense parts of the bus makes this figure even lower. There will be some extra weight as Clark pushes the bus out of the water, before everything drains out, but he certainly never has to lift dozens of tons of water.

Nuclear Hoagie
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Disclaimer: I know absolutely nothing about the film you're referring to. This is a purely physical answer.

According to Google, the average volume of a school bus is 960 cubic feet or about 27 cubic metres. The density of water is around 1 gram per cubic centimetre or 1 tonne per cubic metre, so the answer to your first question

how much additional weight would the water have added to the Bus

is about 27 tonnes.

As for your second question, lifting such a weight certainly requires superhuman strength. To find out just how superhuman, in terms of comparisons with other inhumanly strong characters, you may find this list interesting.

Rand al'Thor
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  • I think it may have been a short bus. – Wad Cheber Sep 28 '15 at 23:21
  • @WadCheber How short? I can do some more fancy calculations if necessary... – Rand al'Thor Sep 28 '15 at 23:23
  • This short: http://www.youtube.com/watch?v=uo23u8Th3A0 – Wad Cheber Sep 28 '15 at 23:24
  • It looks to be about half the length of a normal bus. – Wad Cheber Sep 28 '15 at 23:27
  • @WadCheber Hmm. But Richard's estimation of the weight of water is larger than mine, even though he's going by a "short" school bus and only 90% filled! – Rand al'Thor Sep 28 '15 at 23:32
  • @randal'thor - I used the internal maeasurements provided by this site (https://heritagemath.wordpress.com/2012/01/14/how-many-golfballs-can-fit-in-a-school-bus/) and divided by 70% – Valorum Sep 28 '15 at 23:33
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    Even if you can lift 27 tonnes, you still can't lift a bus filled with water that weighs 27 tonnes, as busses aren't made to stay in one part when they they have 27 tonnes of pressure resting on two points (Superman's hands). Trying to explain superhero mechanics is a one-way train to ouch-my-headville. – Theik Sep 29 '15 at 07:10
  • Plus there is water pressing down from above (and filled with water the bus will have very little or no buoyancy), so there is even more weight. – Eike Pierstorff Sep 29 '15 at 07:53
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    @Theik But it was underwater originally, supported all around so not all the pressure was on his hands; and by the time it rises above water, most of the water has drained out from inside. – Rand al'Thor Sep 29 '15 at 09:15
  • Superman is not on the list that you linked in your article. It only lists Marvel superheroes. – Jason Hutchinson Sep 29 '15 at 20:19
  • @JasonHutchinson Yes: that list is to compare 27 tonnes with how much other superheroes can lift. – Rand al'Thor Sep 29 '15 at 22:50
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Bus

According to School Transport Online, a US "short" school bus has a kerb weight of approximately 10 tonnes.

Water

Factoring in that the bus was around 90% filled with water and has an internal volume of around 7-10,000 gallons that's an additional 8000-9882 (US) gallons of water or around 34-37.4 tonnes of water

enter image description here

Passengers

There are 5 passengers and a driver. There are two slender girls (weight approx 40-45 KG x 2), an adult driver (83Kg), two average weight males (50Kg x 2) and an overweight male (60Kg), that adds an additional .28 of a tonne in weight.

Etc

We can add an additional .1 of a tonne for stowage and .1 of a tonne of fuel and that comes to an approx total of

45-53.88 tonnes of dead weigh lifted by Clark/Superman

Valorum
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  • No stowage area on US buses. – Wad Cheber Sep 28 '15 at 23:28
  • @WadCheber - I'm assuming they had school bags, clothing, etc that needs to be factored in – Valorum Sep 28 '15 at 23:29
  • Just backpacks. Figure 75 pounds altogether for the bags. At most. There are legal limits in some areas for the total weight a student can carry. – Wad Cheber Sep 28 '15 at 23:29
  • Books are heavy. They may have also been carrying musical instruments or other sporting equipment. – Valorum Sep 28 '15 at 23:30
  • I'm going by what I see and what I experienced. A student rarely carries more than 15 lbs, usually much less. It really doesn't matter much anyway. We're arguing over a tiny fraction of the total weight. – Wad Cheber Sep 28 '15 at 23:32
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    @WadCheber - True. The question for me is whether the seat would have filled with water. Assuming they did (x 15 seats) you're looking at an additional plus or minus of nearly a tonne – Valorum Sep 28 '15 at 23:35
  • Objection, m'lud! You've calculated the total volume of water based on assuming the bus contains seats but no passengers. You need to subtract a weight of water corresponding to the passengers' volume before adding on the passengers' weight. – Rand al'Thor Sep 28 '15 at 23:36
  • Presumably, since humans are 80% water, each person weighs 80% of what their volume in water would weigh. – Wad Cheber Sep 28 '15 at 23:39
  • That's nonsense. I'm disgusted with myself for saying it. – Wad Cheber Sep 28 '15 at 23:40
  • @randal'thor - Until we can ascertain the dead weight of the seating (does it fill with water??) the weight of the passengers is a sideshow – Valorum Sep 28 '15 at 23:41
  • @Richard - Each seat has foam inside of it, and the foam is exposed at the joints. The foam would absorb a tremendous amount of water, but it would take a while. (Did I mention that I used to drive school buses?) – Wad Cheber Sep 28 '15 at 23:41
  • @WadCheber - And the glove box. – Valorum Sep 28 '15 at 23:42
  • The seats are metal frames wrapped in foam wrapped in fake leather. I would guess that the foam would be totally saturated after about five minutes underwater. – Wad Cheber Sep 28 '15 at 23:42
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    I'm going to need a bus, five kids and some water to answer this one. – Valorum Sep 28 '15 at 23:43
  • Usually, there is no glove box. The (enormous) heating unit takes up that space. – Wad Cheber Sep 28 '15 at 23:44
  • There is sometimes a double wall structure - a narrow gap between the inner and outer walls. That would add a significant amount of weight as well, unless the gap was filled with styrofoam, which often the case. The additional weight might be as much as half a ton or more. – Wad Cheber Sep 28 '15 at 23:46
  • And don't forget that he's lifting underwater, which should negate some of the weight. Both doors are open, so the water drains as the bus rises above surface level. – Wad Cheber Sep 28 '15 at 23:49
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    What about overcoming surface tension and drag? –  Sep 29 '15 at 02:07
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    I say we get this man a bus. – CandiedMango Sep 29 '15 at 03:29
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    @WadCheber - average human density is within a few percent of the density of water (985kg/m^3 for a person versus 1000kg/m^3 for pure water or 1020kg/m^3 for seawater), so the volume of the humans in the bus can be ignored, they can be treated as if they were water. – Johnny Sep 29 '15 at 04:31
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    USer31418 - From what I have heard, Clark Kent/Superman's strength is like the ID Monster using the Krel Machine in Forbidden Planet.

    And so on. Clark Kent/Superman can use ten to the fourth

    So unless the question is about a version where Clark Kent/Superman has much more limited powers and strength than usual, a version which comes much closer to scientific possibility than usual, I fail to see the point of the question.

     – M. A. Golding Sep 29 '15 at 05:35