He pushes a can over the scaffold at 15 meters and it takes 3.25 seconds for it to land.I keep doing the problem over and over. the Correct answer is 20.5 m/s, however I keep arriving to the solution of 17 m/s. I solved it by doing Vf^2 = Vi^2 + 2adwhere the initial velocity is zero and the acceleration is -g. I made my coordinate system so that down is negative in which the distance will be negative. This however, did not give me the correct answer. Am I right or is the book right?
The initial velocity is not zero since the scaffold is moving upward when the can gets pushed over. And final velocity, vf, does not represent the speed of the scaffold (if that is what you're trying to solve). y = (vo)(t) - (1/2)gt? 15 m = (vo)(3.25 s) - (1/2)(9.81 m/s?)(3.25 s)? vo = +20.5 m/s
