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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?

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  • Are you asking how much a bus weighs if it's filled with water? – Valorum Sep 28 '15 at 23:10
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    Seven. He has to be seven strong. – Wad Cheber Sep 28 '15 at 23:20
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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.

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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.

  • 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: youtube.com/watch?v=uo23u8Th3A0 – Wad Cheber Sep 28 '15 at 23:24
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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 7:10
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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 9:15
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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

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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

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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
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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
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    What about overcoming surface tension and drag? – user31178 Sep 29 '15 at 2:07
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    I say we get this man a bus. – CandiedMango Sep 29 '15 at 3:29
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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 4:31

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