The coefficient of friction between a surface and a block in .41. Determine the angle needed for a 2kg block to slide down the plane with a constant speed. Well after drawing a free body diagram I really couldn't see any way to go about solving. So i decided to name what i knew. I know the massc in 2kg or 20N. I know the coefficient of friction is .41. I remember a concept saying tan(angle)= coefficient of friction. But that seems to direct. If you did use the tangent method the angle would be 23. But then why would the information about the weight be included?