Any question answered...

Depends on the body of water and whether or not you're sinking I suppose

Isn't it the case that Pascal lets you calculate the pressure on the car door, but the principle behind not being able to open the car door is Bernoulli's?

And when there is equalisation of pressure, the door will open? Like a canal lock gate?

I only studied one module of Fluid Mechanics, and didn't exactly set the Engineering faculty alight, so I'll sit here and wait to be corrected. :D

the principle behind not being able to open the car door is Bernoulli's?

Seems unlikely, Bernoulli is to do with fluid flow, and you're probably not trying to open the car door while moving. Also, if the fluid is flowing around the car, that should lower the pressure which is holding the door closed.

when there is equalisation of pressure, the door will open? Like a canal lock gate?

Yes, you just wait for the car to fill with water and then you can get out. Or not, since opinions vary. From a physics point of view, the less the difference between the water levels inside and outside, the less force there is holding the door closed, you only have to wait until you can overcome the force. Ideally, you reach this point before the water gets to nose level🙂

or just open the windows

Or drive a cabriolet (or a motorbike).

open the windows

If the windows can be opened. If the water is over the roof, the windows are being pressed so hard against the inner seals that the electric motor will stall.

Electrics are probably shot at this point anyway

I've been asked to build a 'p rail' but I'm struggling to find a rigid plastic pipe with a 40-50mm outer diameter that has a suitable wall thickness that it doesn't compress massively when you stand on it (say ~60kg in skates). B&Q's standard waste/drain pipes seem to have a wall thickness of 2-3mm. I've found some "high" pressure PVC pipe online but even that only goes up to around 3.7mm wall thickness.

I think early polo mallets used to be made from something more robust, but I haven't seen any of that pipe "going spare" at any of the building sites on my way to work. Where else should I be looking for this? Is there another type of pipe I should be searching for?

My other thought was packing the pipe with something. I figure sand or concrete would work, but would probably increase the weight too much for it to be easily carried to the local park. Expanding foam is probably not sturdy enough. What else might work?

We used to use 50mm blue MDPE water pipe or scaffolding for coping BITD. Both as tough as all hell.

and didn't exactly set the Engineering faculty alight

well, to be fair, water extinguishes simple fires.

If the windows can be opened.

If you're not panicking then the headrests in most cars can be removed and the metal spikes on them are specifically designed to allow you to smash a side window from inside, even when the inside is completely full of water.

even when the inside is completely full of water.

Once the inside is full of water, you can open the doors 😀

Bit iffy in the electrical engineering department.

Didn't top gear, Richard Hammond in particular, test the theory by putting a car in a pool.

Shame it wasn't Clarkson in concrete boots.

This is true, having an air filled car interior when you rupture the windows will send a gush of water in.

You could get 12' of HDPE hot water pipe delivered for not a lot of money.

Edit: 12' not meter!

Once the inside is full of water, you can open the doors 😀

It's not that simple. Mythbusters tested it and with a sample size of n=1 they weren't able to open the doors as quickly as they needed. Seems the cabin has to be completely full of water and since most cars tend to sink nose first there is usually a pocket of air at the back long after the front area has filled up, you'd need to hold your breath way longer than you think.

https://www.youtube.com/watch?v=2YaMEW30bv4

i need a 0.8mm shim for a 25.4 to 26.2 seatpost. before i spend £16 on a shim from the cycle clinic just wondering if there's another (cheaper) solution? :,)

If the limiting survival factor is holding one’s breath while the cabin floods, perhaps it’s best to flood the cabin quickly by opening the windows at the start? You’d sink quicker but there would still be some air in the carriage body to slow the descent.

Allowing the interior to flood slowly risks a trapped air bubble keeping the doors closed. If you sink below 30m, even if you managed to breath from an air bubble, your risk of nitrogen toxicity/ narcosis increases significantly.

The sooner you open a door or window the sooner you can get out, yes. The problem I suppose is getting that done within a second or two when you might be disorientated from just having been in a car crash

Got a link? My search skills are failing but I keep finding 50m+ coils

https://www.pipekit.co.uk/pipe-blue-50mm-sdr11-pe80-x-6m-length.html

+atk Seems like the original listing/seller is no longer on ebay but the below is pretty similar, collection from Derby only though.

https://www.ebay.co.uk/itm/195766441433

Try here: https://www.unitedutilities.com/planned-works-results/