Can a person be moving in a positive direction even if their acceleration vector is negative ?

Asystematic approach to problem solving is called a (an)

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?

Which of these are physical changes in matter? check all that apply. boiling water a pencil being sharpened exploding dynamite freezing water rotting cheese