Why is the voltage of the supply decrease before entering our homes​

According to newton’s first law of motion, which force is expected to cause a body to accelerate?

It is really hard for me right know

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?