Acircular rod with a gage length of 4 m and a diameter of 2.3 cm is subjected to an axial load of 70 kn . if the modulus of elasticity is 200 gpa , what is the change in length?

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.