This applet demonstrates the component forces acting on an object undergoing sloped acceleration. Fg (the net force of gravity) can be decomposed into Fgx (the force of gravity in the direction of the slope) and Fgy (the force of gravity opposite the direction of the normal force). Fgy in turn causes the normal force, which generates Ff (a frictional force). Ff and Fg together determine the net force on the object in the direction of motion, causing the object's acceleration on the slope.

To change the angle of the slope, drag the point on the slope.
To move the slope, drag the horizontal line.
To change the mass of the box or the coefficient of kinetic friction, drag the sliders.
To show (or hide) the various forces acting on the box, check (or uncheck) the appropriate options.