Science Buddies: "Ask an Expert"

I just completed the "Measure Your Magnetism" experiment and I have some questions about what it means for the magnetic field strength to be a negative number. I got a value of 2.45 for v0 then for the 1st magnet I got v1 to be 4.71. When I calculate B using the formula provided, I get a negative value. Does it make sense for B to be negative? Also, if one magnet has B = -452 and another magnet has B = -112, which has the stronger magnetic field strength?

Any time you are dealing with forces, a negative number usually means it's just "going the opposite direction" from whatever you are measuring and declaring to be "positive".

So I would expect a negative field strength to move things in the opposite direction than expected - the field pushes instead of pulling.

The strength is the number, the + or minus is the direction. If you think of it that way you'll arrive at the right conclusion (-442 is stronger than -112. -442 is also stronger than +112, but applies that stronger force in the opposite direction)