Mrs. Davey pushes a 2-kg Physics Book horizontally against the wallIf the coefficient of friction between the book and the wall is 0.15, with what minimum force must Mrs. Davey use to keep the book from sliding down the wall?

Which type of wave can travel without a medium

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.

Give one example to show that when substances are mixed,it may result in a chemical or a physical change depending on the conditions.