Well, I've got the right answer on this problem, but I don't know if/why the math makes sense. I feel like I got the right answer by coincidence. I'm rephrasing the question because it's part of a multipart question. A skier with mass of 100kg starts at point A with a velocity of 31.3m/s. Find the skier's velocity at point B if the distance between A and B is 20m and a constant frictional force of 50N opposes his motion. K=1/2mg2 v=√(v02-2μκmgx Those are the equations I thought relevant. The first equation, K=1/2mg2 is what I used to get the skier's velocity at A (previous part of the problem), which is 31.3m/s. 31.3m/s is correct; I have the answers. Also, from the second equation, √(31.32-(2x50Nx20m)/100kg))=30.98m/s ≈ 31m/s I also know that 31 m/s is correct, because again, I have the answers. But I am particularly confused about why I divided by 100kg. I was trying to find a way to get rid of the "kg" in the Newton unit so I would have like units in both terms. Dividing by 100kg works to make the units match, but I don't understand if/why it works to get the right answer. I appreciate any guidance. Thanks!