Q. A very long solenoid with a circular cross section and radius r= 8.10 cm with n= 1.90E+4 turns/m has a magnetic energy density uB= 5.70 mJ/m3. What is the current in the solenoid?
Q. A 78g, 31 cm long rod hangs vertically on a frictionless, horizontal axle passing through its center. A 15 g ball of clay traveling horizontally at 2.1m/s hits and sticks to the very bottom tip of the rod.
To what maximum angle, measured from vertical, does the rod (with the attached ball of clay) rotate?