When you push a 1.85-kg book resting on a tabletop, you have to exert a force of 2.10 N to
start the book sliding. Once it is sliding, however,
you can use a force of only 1.01 N to keep the
book moving with constant speed.
What is the coefficient of static friction between the book and the laptop?
What is the coefficient of kinetic friction between the book and the tabletop?

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.