a whole of area 200 mm at the bottom of a tank 4 metres deep is closed with with a cork determine the force due to water when the density of water is 1000 kg per metre cube and acceleration due to gravity is 10 m per second squared ​

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.