(multiple choice) A cannon fires a cannonball. What happens to most of the chemical energy of the explosives?
A. It transforms into kinetic energy.
B. It transforms into elastic potential energy.
C. It transforms into electrical potential energy.
D. It transforms into gravitational potential energy.

Ametal ring 4.20 cm in diameter is placed between the north and south poles of large magnets with the plane of its area perpendicular to the magnetic field. these magnets produce an initial uniform field of 1.12 t between them but are gradually pulled apart, causing this field to remain uniform but decrease steadily at 0.240 t/s . (a) what is the magnitude of the electric field induced in the ring? (b) in which direction (clockwise or counterclockwise) does the current flow as viewed by someone on the south pole of the magnet?