An object traveling at constant speed v in a circle of radius R has an acceleration a = 5 m/s2. If both Rand v are doubled, what is the new acceleration? 40 m/s^2
10 m/s^2
5 m/s^2
2.5 m/s^2

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?