You are running to catch a train which is stationary on the tracks. The whistle is blowing, in preparation for the train’s departure. Describe the sound you hear as you run very quickly to catch the train.

Cathy is pedaling down a steep hill on her bicycle and wants to be able to coast up the next hill, which is 25 meters high, without pedaling. cathy and her bicycle have a mass of 75 kg. assuming her bicycle is 100% efficient, what would her speed have to be?