A little girl (30 kg) goes sledding with her friends. The hill the girl starts on is 7 meters tall. She reaches a speed of 6.26 m/s when she is 5 meters above the bottom of the hill. What is her mechanical energy when she is 5 meters above the ground?

Consider a production line with five stations. station 1 can produce a unit in 9 minutes. station 2 can produce a unit in 10 minutes. station 3 has two identical machines, each of which can process a unit in 12 minutes (each unit only needs to be processed on one of the two machines. station 4 can produce a unit in 5 minutes. station 5 can produce a unit in 8 minutes. which station is the bottleneck station?