Which one is the answer ?

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?

Why do atoms emit energy of only specific wavelengths

Meaning of a nonzero y-intercept to a graph of reaction distance versus speed