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Random thought of the day. What would boats be like if gravity was greater than it is?
In terms of floatation? Would make no difference.
A boat displaces its own mass in water. Whatever gravity was, the mass of both the boat and the water would be unchanged.
Does a viaduct 'notice' when a canal boat is on it?
Does a viaduct 'notice' when a canal boat is on it?
My guess:
Analysing the statics, [s]no[/s] yes. The body of water on the viaduct is a fixed amount between the upstream and downstream lock gates. The mass of the boat is added, the water is displaced, and the level rise is dependant on the area , ie the distance between the gates.
Analysing the dynamics, yes. Of course. Moving boat produces variable forces. Even if the boat is not moving, the hydraulic flow of water through the viaduct will be change by the addition of the boat. All waterway's have a (minimal) flow even when lock gates are shut.
Does a viaduct 'notice' when a canal boat is on it?
<pedant>nope, boats don't go on viaducts, they go on aqueducts 😛
Biscuit Powered - Member
In terms of floatation? Would make no difference.
What about in a storm? Would different designs be needed?
miketually is correct, it would make no difference due to archimedes principle, namely that a floating object displaces its own weight in water.
have a look at the falkirk wheel, hundreds of tons of water/boat, but only uses the same power to lift/lower a boat/boats as boiling 8 kettles of water.
Biscuit Powered - Member
Does a viaduct 'notice' when a canal boat is on it?
<pedant>nope, boats don't go on viaducts, they go on aquaducts
If you plan on being a pedant, at least learn to spell the word "aqueduct".
😉
If you plan on being a pedant, at least learn to spell the word "aqueduct".
Realised as soon as I clicked post and edited
Not quick enough though it seems 😉
My quote-fu is strong! 🙂
pentant ii)
Aqueduct - a viaduct that transports water 😉
They would have to be a little stronger, because the pressure on the sides would be greater....
A boat displaces its own mass in water. Whatever gravity was, the mass of both the boat and the water would be unchanged.
Since we're being pedants on this thread, a boat displaces it's own [b]weight[/b] of water, both will change but remain equal. The [b]mass[/b] won't change (as observed in it's local frame of reference, of course, for the relativistic hyper-pedants on the forum)
Analysing the statics, yes. The body of water on the viaduct is a fixed amount between the upstream and downstream lock gates. The mass of the boat is added, the water is displaced, and the level rise is dependant on the area , ie the distance between the gates.
Except that the amount between the upstream and downstream gates isn't fixed (what happens when the downstream lock is empty and you have to fill it?), and you don't drop the boat straight into that body of water, it floats in from a lock when the gates are opened, at which point the total mass of water/boat between the locks is unchanged - the water the boat displaces goes into the lock instead.
The only reason adding a boat makes any difference to the water level is because you have to operate the locks. One way to look at this is to consider boats coming from the upper pound via the upper lock. When the lock is emptied into the pound with the aqueduct, the amount of water being transferred is the same whether there are 2 boats in the lock or only 1 (or none, but then you wouldn't be emptying the lock). Clearly when you open the lower lock gate of the upper lock the water level doesn't change. When you float the boat(s) out of the lock the water level doesn't change. Therefore the second boat being in the lock makes no difference at all to the static water pressure on the viaduct compared to there only being one boat in the lock.
Of course the other point is that there is no difference in static pressure on the aqueduct when the boat is on it or when the boat is on another part of the pound which isn't on the aqueduct.
Where else could I go to experience gravity related canal pedantry?
Wonderful place..