Force on a ferromagnetic object

[mahela007]

How can one calculate (even as a rough estimate) the force exerted on a ferromagnetic object by a magnetic field created by a solenoid? Thanks

 

[Vanadium 50]

With great difficulty, since it depends on the gradient of the field, which is not simple for a solenoid.

 

[mahela007]

oh well..
Just for the sake of knowledge, does the gradient of the field come into play because all magnets have two poles and because the net force depends on the difference between the force on each end?

 

[Vanadium 50]

Yes - although in this case it's more complicated, since you need to induce a magnetic dipole in the object.

 

[mahela007]

well, I asked this question because I'm building a simple DIY coilgun.. (just 8J of energy stored in the caps). So I'm going to have to resort to trial-and-error. Thanks for your help.