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## Homework Statement

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?

## Homework Equations

## 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

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