Skip to main content

Jungle Speed vs Solids with Known Cross Sections

As a kid, I played a game called Jungle Speed. Here's a picture for reference, but essentially everyone playing flipped one card over at a time and when a specific pattern appeared, your goal was to grab the yellow stick before anyone else could. Well, when I thought about calculating the volume of a solid with known cross sections, the first thing that came to mind was that yellow stick. I know that sounds really random, but that's what I decided to try and recreate.

The cross sections of the yellow stick are circles, but in order to better explain cross sections I chose to use rectangular prisms as my cross sections as they are easy to visualize and have a basic volume equation. I now had to think about what equations could make up the wave like sides of the yellow stick and I figured a trig function would be best suited for a wave like shape. I chose the following functions and evaluated the volume of known cross sections of squares between \(x=0\) and \(x=10\):

\[f(x) = cos(x) + 2\] and \[g(x) = sin(x)\]

In order to approximate the volume of my solid with square cross sections, I had to calculate the volume of each of my ten rectangular prisms and add them together. Since the volume of a rectangular prism with a square base is \(V=b^2*h\), I calculated the difference between \(f(x)-g(x)\) to be my base and used a height of \(1\) for each prism to ensure an even spread. I used the midpoint of each cross section to get the most acurrate volume of my object. Below is a table showing a summary of my calculations and the total approximate volume of \(39.71units^3\):



In order to calculate the actual volume of my solid, I had to calculate the integral of the area of each cross section with respect to \(x\). The integral below shows the actual volume of my solid is about \(40.17units^3\):

\begin{aligned}\int _{0}^{10}\left[ \left( \cos x+2\right) -\sin x\right] ^{2}dx\\ .\end{aligned} \begin{aligned}=\int _{0}^{10}\cos ^{2}\left( x\right) +400s\left( x\right) -2sin\left( x\right) \cos \left( x\right) -4\sin \left( x\right) +sin^{2}\left( x\right) +4dx\\ =-\sin ^{2}\left( 10\right) +4\sin \left( 10\right) +4\cos \left( 10\right) +46=40.17units^{3}\end{aligned}

The solid that I ended up creating looked a little less like the yellow stick from my game and a little more like when the kid you babysit doesn't understand physics and tries to make a tower with their blocks. But, you can definitely still see the wave like sine and cosine functions that I wanted to see, so it wasn't a total fail. The image below shows the solid I will attempt to print. Once I created my solid, I scaled it down to 40% to create the dimensions \(101.7mm\) x \(40.28mm\) x \(34.69mm\).

Comments

Popular posts from this blog

Knot 9-31

Knot 9-31 A knot is mathematics is defined as a closed, non-self-intersecting curve that is placed in three dimensions and cannot be the "unknot". The main difference between a knot in the real world and a known in mathematics is that a knot in mathematics does not contain any extra strands. The example following will help visualize this. Today, I have specifically chosen knot 9-31 from the Knot Atlas. This knot is very unique and contains some very interesting properties that we are going to look into. The Crossing Number For my knot today, I chose knot 9-31 from the Knot Atlas. This knot contains 9 crossings! The Unknotting Number The unknotting number is exactly what is sounds like. This is the minimum number of times the knot must be passed through itself to untie it. Luckily, the Knot Atlas is super useful and provides the unknotting number for us, but I still...

Do Over: Integration for Over Regions in the Plane

Introduction Earlier in the semester, we visited the topic of integration for over region regions in the plane. This was our first experience with taking integration in the third dimension. To do this, we had to use double integrals to calculate the volume of a region between two surfaces. This topic seems relatively straightforward and anyone who has taken a higher calculus class knows of double integrals. Today, we are going to revisit this topic for a couple of reasons. Why Double Integrals Again? As mentioned before, I am revisiting this topic for a couple of reasons. One of the main reasons is due to how the 3D print turned out. Due to the function, I chose, the final rectangular prism was stand alone. When printing, this resulted in a sloppy prism that lacked structural integrity. The image below is a reference to my original design that includes the prism that had the issue. The main cause of ...

Middle of Mass Measured from Moment

The center of mass of an object is the point that lies in the average position of mass in that object. For a normal polygon, that point is in the middle of the shape. However, if the shape is irregular, has concave angles, or has holes, the center of mass can be far from the middle of the object. Two things come into factor when determining the center of mass of an object. Weight and distance. Obviously, if one side of an object has more mass than the other, the center of mass will be on the heavier side. But, distance plays a role, too. If two sides of an object have the same mass, but one is farther from the middle, the center of mass will be on the side that has farther mass. Multiplying both of these factors together gives the moment of an object. Dividing the moment by the overall mass gives the location of the center of mass.   The reason I chose my shape is to mimic how those toy balancing birds work. The toy is a model bird with its wings outstretched. The ...