What is Cone: Definition and 511 Discussions

A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex.
A cone is formed by a set of line segments, half-lines, or lines connecting a common point, the apex, to all of the points on a base that is in a plane that does not contain the apex. Depending on the author, the base may be restricted to be a circle, any one-dimensional quadratic form in the plane, any closed one-dimensional figure, or any of the above plus all the enclosed points. If the enclosed points are included in the base, the cone is a solid object; otherwise it is a two-dimensional object in three-dimensional space. In the case of a solid object, the boundary formed by these lines or partial lines is called the lateral surface; if the lateral surface is unbounded, it is a conical surface.
In the case of line segments, the cone does not extend beyond the base, while in the case of half-lines, it extends infinitely far. In the case of lines, the cone extends infinitely far in both directions from the apex, in which case it is sometimes called a double cone. Either half of a double cone on one side of the apex is called a nappe.
The axis of a cone is the straight line (if any), passing through the apex, about which the base (and the whole cone) has a circular symmetry.
In common usage in elementary geometry, cones are assumed to be right circular, where circular means that the base is a circle and right means that the axis passes through the centre of the base at right angles to its plane. If the cone is right circular the intersection of a plane with the lateral surface is a conic section. In general, however, the base may be any shape and the apex may lie anywhere (though it is usually assumed that the base is bounded and therefore has finite area, and that the apex lies outside the plane of the base). Contrasted with right cones are oblique cones, in which the axis passes through the centre of the base non-perpendicularly.A cone with a polygonal base is called a pyramid.
Depending on the context, "cone" may also mean specifically a convex cone or a projective cone.
Cones can also be generalized to higher dimensions.

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  1. R

    Volume of a cone by integration

    Can anyone help me with this question? A uniform solid cone of height b and base radius a stands on a horizontal table. Find an expression for the volume of the disc at height h above the base. Integrate over all the discs to show that the total volume, V, is given by V =pi/3 * b * a^2
  2. R

    Integration of a cone to find centre of mass

    Can anyone help me with this question? A uniform solid cone of height b and base radius a stands on a horizontal table. Find an expression for the volume of the disc at height h above the base. Integrate over all the discs to show that the total volume, V, is given by V =pi/3 * b * a^2
  3. C

    What is the optimal angle for a conical cup with a maximum volume?

    A conical cup is to be made by joining the edges OA, OB of the sector of a circle of radius 8cm. What angle @ gives the cup of maximum volume? I'm having trouble solving this question. This is what I have done so far we know V=pi*r^2*h/3 r is given, so we need to put h in terms of...
  4. S

    Electic potential on a cone

    Thanks for taking the time to look at this. I'm getting ready to go to grad school, and I'm realizing that although I did ok in my classes, there are large gaps in my knowledge of physics. That said, I'm currently trying to work my way through an E&M book, and now I'm stuck. Here's the...
  5. L

    Have a cone and divide it into infinately small slices

    If I have a cone and divide it into infinately small slices. Wouldn't both sides of one slice have the same area and wouldn't the next slice (and so on) have the same area as the slice before. So wouldn't your cone actually be a cylinder? My answer is no, because the reasoning is wrong. If I...
  6. M

    Calculating Center of Mass of a Hollow Nose Cone

    I am working on a rocket and need to find the center of mass of a hollow nose cone. Any help would be appreciated.
  7. A

    Volume of region bounded by cone and parabloid

    I don't know if anyone will be able to help me, I am really stuck on this question! "Show that the volume of the region bounded by the cone z=sqrt((x*x)+(y*y)) and the parabloid z=(x*x)+(y*y) is PI/6" The bits in the brackets (ie x*x and y*y) are x squared and y squared respectively and...
  8. T

    How Can I Understand the Dynamics of a Conical Pendulum?

    Conical Pendulum Can anybody explain everything about the Conical Pendulum (Not Simple Pendulum), 1. Distance 2. Velocity 3. Acceleration 4. Energy and it's conservation 5. Frequency 6. General Equations And everything related to it, I need them as step by step, for example start...
  9. P

    A right circular cone is inscribed in a hemisphere.

    A right circular cone is inscribed in a hemisphere. The figure is expanding in such a way that the combinded surface area of the hemisphere and its base is increasing at a constant rate of 18 in^2 per second. At what rate is the volume of the cone changing when the radius of the common base is 4 in?
  10. K

    Does Travelling at Light Speed Turn the Time Cone into a Cube?

    Time is on the y-axis and distance is on the x-axis and z-axis. Depending upon your velocity the cone is formed. At, let's say 1/10c, you can reach point "A" in ten years and your cone is narrow, but at 1/5c point "A" is 5 years away and the cone is wider. At 1/2c you could be at point "A" in...
  11. C

    Fluid flow through a cone equation ?

    I'm in the process of designing a scoop used for automotive purposes. Anybody know some formulas pertaining to pressure, velocity and area dealing with scoops (Funnels, cones, etc)? Thanks for the help! Joe
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