Posted by Matt on .
A 5.20 package slides 1.57 down a long ramp that is inclined at 13.0 below the horizontal. The coefficient of kinetic friction between the package and the ramp is = 0.305
Calculate the work done on the package by friction.
Calculate the work done on the package by gravity.
Calculate the work done on the package by the normal force.

physics 
Elena,
W(fr) = F(fr) •s=μ•mg•cosα•s=0.305•5.2•9.8•cos13°•1.57 =
W(gr) = m•g•h=m•g•s•sinα=5.2•9.8•1.57•sin13° = …
W(norm) =N•s•cos90°=0