Finding volumes of revolution using centroids

In summary, in Cal II we are learning about finding volumes of revolution using centroids, which are found using moments of x or y. A moment is represented by the quantity M = int( x*f(x) dx) from a to b and has a physical interpretation as the tendency of a force distribution to cause rotation about a reference point. It can be thought of as a vector quantity that measures an object's ability to rotate around a point due to an applied force at a specific distance. It is similar to torque.
  • #1
Towk667
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In my Cal II, we're discussing finding volumes of revolution using centroids, which we find using moments of x or y. Can someone explain to me what a moment is?
 
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  • #2


If you think of a function f(x) defined over the interval from a to b, then the moment of this function with respect to the origin is

M = int( x*f(x) dx) from a to b
 
  • #3


No, thanks though, I know how to solve for a moment over an interval, I'd like know what a moment actually is.
 
  • #4


A moment is just that quantity. If you know the definition, then you know what a moment is.

It has a physical interpretation also, but that is not likely be be a part of a calc class. If f(x) represents a force per unit length, then the moment represents the tendency of that force distribution to cause a rotation about the reference point.
 
  • #5


Moment is essentially a vector quantity that tells you about an objects ability to rotate about a point by some given force at some given distance. If you know what a torque is they're pretty much the same.
 

1. What is the concept of "volumes of revolution"?

The concept of "volumes of revolution" is a mathematical method used to find the volume of a three-dimensional object created by rotating a two-dimensional shape around an axis. This method is commonly used in calculus and engineering to solve problems involving rotational symmetry.

2. What is a centroid and how is it related to finding volumes of revolution?

A centroid is the center of mass of a three-dimensional object. In the context of finding volumes of revolution, the centroid is used as a reference point to calculate the volume of a rotated shape. It is also used to determine the axis of rotation for the shape.

3. What are the steps for finding volumes of revolution using centroids?

The steps for finding volumes of revolution using centroids are as follows:1. Identify the axis of rotation.2. Determine the two-dimensional shape that will be rotated.3. Find the centroid of the shape.4. Set up the integral for the volume of revolution using the centroid as the reference point.5. Solve the integral to find the volume.

4. What are some common applications of finding volumes of revolution using centroids?

Finding volumes of revolution using centroids has many practical applications in fields such as engineering, physics, and architecture. Some examples include calculating the volume of a water tank, determining the mass of a 3D printed object, and designing curved structures such as bridges and arches.

5. Are there any limitations to using this method for finding volumes of revolution?

While finding volumes of revolution using centroids is a useful method, it does have some limitations. This method can only be used for objects with rotational symmetry, and it assumes that the shape being rotated is continuous. Additionally, it may be challenging to determine the axis of rotation for more complex shapes.

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