4 ms·

Oh what about magnetism? Could we wrap the ship in wire and send so much current through that it repels against the Earth's magnetic field and shoots itself ri

Oh what about magnetism? Could we wrap the ship in wire and send so much current through that it repels against the Earth's magnetic field and shoots itself right into the atmosphere? Basically building a giant rail gun. Might need a small nuclear power plant or two to make it feasible.

stordoff 6y ago
I've now got the most amazing image in my head of a container ship being fired at the moon.
- qbasic_forever 6y ago
  Hah or if we reverse the polarity maybe we can crush it into something the size of an aluminum can.
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 ago
  Well, 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 ago
    Upvoting you just due to username
- _Microft 6y ago
  The 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 ago
    Yeah, 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 ago
      Why 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 ago
  Add 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.

stordoff 6y ago

I've now got the most amazing image in my head of a container ship being fired at the moon.

qbasic_forever 6y ago
Hah or if we reverse the polarity maybe we can crush it into something the size of an aluminum can.

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 ago
Well, 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 ago
  Upvoting you just due to username
_Microft 6y ago
The 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 ago
  Yeah, 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 ago
    Why 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 ago
Add 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.