How do you define the principal focus of a diverging lens? A. The place where incident rays parallel to the principal axis converge after they are refracted

B. The place where incident rays appear to have emanated from

C. The place where refracted rays parallel to the principal axis converge after they are refracted

D. The place where refracted rays appear to have emanated from

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?