A 90Kg box is pushed by a horizontal force F at constant speed up a ramp incined at 28 degrees. Determine the magnitude of applied force when the ramp is frictionless and when the coefficient of kinetic friction is 0.18

Answer 1

x-axis - along the ramp, y-axis - perpendicular to the ramp (upwards).

x: F =F(fr) + m•g•sinα,
y: N=mgcos α,
F=μ•N + m•g•sinα = μ• m•g•cos α + m•g•sinα =m•g(μ• cos α+ sinα)