3 ms·
> Might need a small nuclear power plant or two to make it feasible. Amazingly, that's a severe underestimation. The force on a wire carrying current in a ma
by Denvercoder9 6y ago
> Might need a small nuclear power plant or two to make it feasible.
Amazingly, that's a severe underestimation.
The force on a wire carrying current in a magnetic field is given by F = B*I*l, and to move it upwards that force needs to be at least equal to gravity, so equate to F = m*g.
- Let's be generous and assume B = 100 uT = 100 * 10^-6 T.
- Likewise, assume the ship is a rectangular box with sides of 400 m x 100 m, so a circumference of 1000 m, and that we can wrap a wire 100,000 times around it, to give total wire length l = 10^8 m.
- m = 200,000 metric tonne = 2 * 10^8 kg (we assume magic wire that is massless).
- g = 10 m/s^2.
Solving for I yields I = mg/Bl = 2 * 10^5 A. That's a lot of current.
If we assume the wire has a diameter of 10 cm (which is ridiculously high considering we just wrapped it 100,000 times around the ship, but whatever) and is made out of copper, it has a resistance of ~200 Ohms. Necessary power to generate such a current is P = I^2*R = 8*10^12 W (= 8000 TW). That's about half the total energy consumption of humanity.
The largest nuclear power plant puts out about 8000 MW, so you'd need a 1000 of them.
- qbasic_forever 6y agoWell, on the bright side once we free it with this incredible contraption then we've also solved all of humanity's power needs for a few more centuries. :)
- rogerdickey 6y agoUpvoting you just due to username
- _Microft 6y agoThe most important thing here is the magicness of the wire. The ship is 60m wide and 30m tall, that makes a circumference of 180m. 0.05m radius, 100000 windings, made of copper with a density of approx. 8900kg/m^3 gives a total mass of approx. 1.3*10^6 tons for the cable alone.
- Denvercoder9 6y agoYeah, the wire would be heavier than the ship. That is a relatively fundamental result. With current materials, it's pretty much impossible to levitate anything against Earth's magnetic field. You can't put enough current through a wire to create a force bigger than its own gravity without using unreasonable amounts of power. Even if you put in that power, you'd melt the wire.
- nullsense 6y agoWhy don't we just melt the ship? If we turn the whole thing into a liquid it could flow down the canal.
- deleted 6y ago[deleted]
- dghughes 6y agoAdd another 40,000 tonnes for the empty containers, then probably that again for whatever is in them. Plus probably another 10,000 tonnes for fuel. Really it may be conservative to say another 100,000 tonnes for all the stuff other than the 200,000 tonnes of the ship itself.
- Denvercoder9 6y agoThe 200,000 metric tonne figure was derived from the deadweight tonnage, which is the weight of fuel and cargo a ship can carry, but excludes the weight of the empty ship itself. Wikipedia doesn't list displacement (which is weight of the ship plus cargo) for the Ever Given, but empty weight of modern container ships is on the order of 10% of their capacity, so ignoring the ships empty weight isn't the worst approximation used.
- pedrig 6y agoDiscussions like these are why I love HN. Sorry for non-constructive response, but this time I just had to say it. Great laugh.
- gabagool 6y agookay, got it. So that's totally infeasible. what if we "only" had to fire it into the nearby Suez Gulf?
- Denvercoder9 6y agoThis calculation only gives the amount of power needed to cancel gravity. It's the minimum power needed to move it up, even if that's just a millimeter. If you actually want to accelerate it upward to any meaningful speed, you'd need even more power.
- etxm 6y agoSo why are you spending all your time gabbing. Get to work!