The student uses a spring as a spring balance. when the student hangs a stone from this spring its extension is 72mm the spring does not go past the limit of proportionality calculate the force exerted by the stone on the spring the spring constant = n/m

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.