An object weighting 100N is traveling vertically upward from the earth in the absence of air resistance at a constant velocity of 5 m/s. What is the power required to keep the object in motion?
P = ΔE/t and P = Fvcosθ
The Attempt at a Solution
The explanation given in TPR(the princeton review book) is: since the object's velocity is upward and constant and the force necessary to propel the object is also upward and constant we may use the equation: P = Fv = 100N(5) = 500W.
What I don't understand is this: If the velocity is constant, then the force should be zero, and that should make the Power zero too, right?