When is a magnetic force produced in a copper wire? O A. Whenever the wire is connected to a magnet
B. Whenever the wire is wrapped around an iron bar
C. Whenever there is current in the wire
D. Whenever the wire is coiled

Asolid cylinder and a cylindrical shell have the same mass, same radius, and turn on frictionless, horizontal axles. the cylindrical shell has light-weight spokes connecting the shell to the axle. a rope is wrapped around each cylinder and tied to blocks of equal masses that are held the same height above the ground. both blocks are released simultaneously. the ropes do not slip. which block hits the ground first? or is it a tie?