Can we measure the spin of a particle by measuring the force on a Magnet? I wish to consider a modified stern gerlach like apparatus where a Magnet of mass M is attached to a spring. Can we measure Spin of the particle by studying the deflection of the magnet? Even if it is possible, I can see No way to calculate the force on the magnetic. I think the consideration that the spring is composed of several degrees of excitation becomes important to analyze this problem.