Re: Is there a strong enough magnet to either attract or repel a flying bullet

In short, yes your idea would work in principle, but it will be extremely 
difficult to build.  Great idea, you are "thinking outside the box"

Materials fall into one of three magnetic properties: ferromagnetic, 
paramagnetic and diamagnetic. Ferromagnetic materials are themselves 
magnetic (i.e., iron) and will stick to the poles of the magnet. 
Paramagnetic and diamagnetic minerals are not magnetic, but they differ in 
how they interact with a magnetic field. Paramagnetic materials are weakly 
attracted into a magnetic field and diamagnetic materials are weakly 
repelled by a magnetic field. These magnetic responses differ greatly in 
strength. Diamagnetism is a property of all materials and opposes applied 
magnetic fields, but is very weak. Paramagnetism, when present, is 
stronger than diamagnetism and produces magnetization in the direction of 
the applied field, and proportional to the applied field. Ferromagnetic 
effects are very large, producing magnetizations sometimes orders of 
magnitude greater than the applied field and as such are much larger than 
either diamagnetic or paramagnetic effects. 

The problem in creating your protective vest is the extreme magnetic field 
you need.  An iron bullet travelling at high speed would be sufficiently 
deflected from its course only by the strongest magnets we have, which 
weigh many tons.  Most bullets are made of Lead, which is diamagnetic, and 
is weakly repelled by a magnet.  The effect is so weak you would need to 
increase the magnetic field by something like 100,000 times that required 
to deflect an iron bullet.

With todays technology and engineering your vest might weigh thousands of 
tons and require the electrical power of an entire city.  But in theory it 
is possible, and every generation of students goes on to engineer a 
superior technology of magnets.  Perhaps your generation will be the one 
to make this idea practical.

Here are some Ideas:  A lead bullet entering an intense magnetic field 
will have a very strong internal electric current generated by its 
motion.  This current further deflects the bullets away from the magnet.  
The intensity of the current may also cause the bullet to tear apart and 
vaporize. The action of a magnetic fluid like oxygen (yes, oxygen is 
magnetic) can cause lead to be displaced.
physicsweb.org 1
physicsweb.org 2

One more engineering problem to consider: such intense magnetic fields can 
turn ordinary objects into deadly projectiles!  
irc.chmcc.org
radiology.emory.edu

Good luck with your ideas!  The problems are great, and great minds like 
yours will someday solve them.

Best Regards,
Altair
www.altair.oeg