An aluminum sphere (specific gravity = 2.70) falling through water reaches a terminal speed of 8.36 cm/s. what is the terminal speed of an air bubble of the same radius rising through water? assume viscous drag in both cases and ignore the possibility of changes in size or shape of the air bubble; density of air at 20°c is 1.20 kg/m3 and that of water is 998.21 kg/m3.

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.