A hollow cone is put upside-down with its symmetry axis vertical. The surface of it makes an angle of theta with the vertical direction as shown in the figure . A small puck of mass m slides without friction on the inner side of this cone and remains within a horizontal plane as it rotates about the axis of the cone.
EDIT: The question: What is the normal force exerted on the puck by the inner surface of the cone in terms of m, g, and theta?
The Attempt at a Solution
1) Resolve X and Y coordinate so that the surface of the inside of the cone is x and y is perpendicular to that surface.
2) Resolve force of gravity into x and y components.
3) Fy = Fn - mgsin(theta) = 0
Fn = mgsin(theta) (WRONG)
The actual solution
1) Set X and Y coordinate normally
2) Resolve the NORMAL force
3) Fy = Nsin(theta) = mg
N = mg/sin(theta)
So I'm always used to resolving gravity into components when doing force problems, and so I did that.
However, to get the correct solution in this problem