*** my teacher Never actually taught us this stuff so I need to know how to go about solving these problems. Hopefully that helps me figure out the concept enough that I can do well on a test lol 1. A roller coaster car with a mass of 640 kg moves along a section of a track. Assume all friction is negligible. A) if the roller coaster car starts from rest at point A, calculate the speed of the roller coaster car when it reaches point B B) if the roller coaster car starts with an initial speed of 12 m/s at point A, calculate the speed of the roller coaster when it reaches point C 2. Athletes who compete in downhill skiing try to lose as little energy as possible. A skier starts from rest at the top of a 65 m hill and skis to the bottom as fast as possible. When she arrives at the bottom, she has a speed of 23 m/s. Calculate the efficiency of the skier