How many times does your heart beat during your lifetime? round the answer to the nearest power of 10 and then express your answer as the order of magnitude. for instance, if your estimated answer is 3×105, enter 5. if your estimated answer is 8.7×105, you should enter 6 (rounding up to the next power of 10).

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.