Why are biofuels becoming a popular alternative source of energy?

Acave rescue team lifts an injured spelunker directly upward and out of a sinkhole by means of a motor-driven cable. the lift is performed in three stages, each requiring a vertical distance of 10.0 m: (a) the initially stationary spelunker is accelerated to a speed of 4.90 m/s; (b) he is then lifted at the constant speed of 4.90 m/s; (c) finally he is decelerated to zero speed. how much work is done on the 68.0 kg rescue by the force lifting him during each stage?

Aa a of 22 m/s at an of 36.9 .be . a. b. c. (3)x y of? (3)go? (4) () it to to ?

Which radioisotope is used in dating geological formations?