Which of the following changes increases the overall density of the object? (CHOOSE ONE ANSWER OUT OF A, B, C, D) A) A block of iron is formed into hollow shape. B) A submarine fills its ballast tanks with water. C) A submarine fills its ballast tanks with air. D) A fish increases the amount of gas in its swim bladder.

Phase changes are chemical changes. true or false

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?

If an electric circuit is not grounded it is best to reach out and touch it to provide the ground a.true or b.false