(a) What is the practical purpose of a compass? What does a compass measure?
(b) Indicate several things you notice. When the bar magnet is placed on the board, are the compasses still measuring what you indicate in part (a)? Explain your answer.
(c) Draw a bird’s eye view of the white-board. Draw arrows in the location where compasses are placed. Arrows should point towards the red end of the compasses' needles.

When the force acting on an object points at least partially in the direction of the motion the work done is considered to be negative

An object weighs 40n in air, weighs 20n when submerged in water and 30n when submerged in a liquid of unknown density. what is the density of the liquid?

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.