Which statement best describes the big bang theory? a. the universe began as a ball of energy and has been collapsing since its formation. b. the universe began as a cloud of dust and gas and has been expanding since its formation. c. the universe began at an outer boundary has been collapsing since its formation. d. the universe began at a single point and has been expanding since its formation.

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?

It is really hard for me right know

Suppose a soccer ball is kicked from the ground at an angle 20.0º above the horizontal at 8.00 m/s. the y-velocity is determined to be 2.74 m/s. how long will the ball be in the air? assume the ball lands at the same height at which it was kicked.