What do the amplitude and frequency of a sound wave determine?

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?

Difference between series and parallel circuits

The voltage applied across a given parallel-plate capacitor is doubled. how is the energy stored in the capacitor affected?