Here's the question you clicked on:
bob1
Consider a ball rolling down an inclined plane. The normal force on the ball is what?
it will be perpendicular to the plane's slope.
As there is no acceleration of the centre of mass perpendicular to the plane, the corresponding net force is zero. Hence normal force equals weight times cosine of the angle.
@rvgupta What you have just written is the component of weight ALONG the plane, not NORMAL to it.