4.One rubber tire can generate about250,000 BTUS (1BTU=.0003KW ) when it is burned. The average American home consumes about 10,000 kWh of electricity per year. How many tires would be needed to meet the annual electricity demand of ten homes for one year if the production of electricity from tires is 50% efficient??

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?

Coal contains energy. a. light b. kinetic c. chemical d. mechanical

The gravitational force between pluto and charon is 3.61 × 1018 n. pluto has a mass of 1.3 × 1022 kg, which is only slightly greater than charon’s mass of 1.6 × 1021 kg. how far apart are pluto and charon? 2.0 × 107 m 2.4 × 1012 m 3.8 × 1014 m 5.8 × 1024 m