Imagine a finite length solenoid with outer radius R1 and inner radius R2. This solenoid has a time-varying current going though it. This solenoid is also fixed so that it cannot move. Now imagine another solenoid, coaxial with the first, with its outer radius equal to R2 such that it can slide in and out of the first solenoid. The ends of this solenoid are connected together and no current is being externally applied to it. The only current going through it is the induced current from the first coil. My question is, would it be possible to calculate the magnetic force on this solenoid? Or is this a problem that would need to be solved numerically?