We have a radioactive isotope called ri which has a half-life of 12 million years. a geologist has used radiometric dating and determined the rock to be approximately 36 million years old. how many half lives have taken place?

The free body diagram shows a box being pulled to the left up a 25-degree incline. the magnitude of the normal force is

Avoltaic cell converts chemical energy to

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?