Normal force acting on an loop?

[slammer]

Im trying to find the normal force that acts on an roller coaster when going aruond a loop. when the roller coaster is at the top the Fn is always 0 right? And is that the only time its 0?

 

[nrqed]

Im trying to find the normal force that acts on an roller coaster when going aruond a loop. when the roller coaster is at the top the Fn is always 0 right? And is that the only time its 0?

Np. it is not necessarily equal to zero! It's zero only if it is just about to fall (or, in other words, if it barely made it through th eloop)