Questions 4-6 refer to the following material. A ball swings freely back and forth in an arc from points I to IV, as shown. Point II is the lowest point
in the path, III is located 0.5 m above II and IV is I m above II. Consider air resistance to be negligible.
IV
111 10.5 m
4. If the potential energy is zero at II, where will the kinetic and potential energies of the ball be equal?
A) At point II
B) At some point between II and III
C) At point III
D) At some point between III and IV

What is the most useful equation for electric power?

A100-watt light bulb illuminates a solar cell. the electricity from the solar cell operates a water pump that delivers 1 watt of power. what is the efficiency of the system?

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?