According to the nebular hypothesis, when did nuclear fusion begin? (2 points)
after the planets formed.
when the sun was 5 billion years old.
when the nebula first exploded outward into space.
when particles were pulled together so tightly they combined.

Identify the forces that contribute to the centripetal force on the object in each of the following examples: a. a bicyclist moving around a flat, circular track b. a bicycle moving around a flat, circular track c. a racecar turning a corner on a steeply banked curve

The pressure proportional to the area a- inversely b- directly c- increase d-decrease

Complete these sentences. if a roller coaster train has a potential energy of 1,500 j and a kinetic energy of 500 j as it starts to travel downhill, its total energy isj. once the roller coaster train gets closer to the bottom of the hill, its kinetic energy increases to 1,100 j, and its potential energy decreases to j. when the train reaches the bottom of the track and is traveling along the ground, its kinetic energy isj.