Author Archives: mathscinotes

BB Ballistic Coefficients

Posted on 29-December-2020 by mathscinotes

A number of years ago, I was asked by a father to assist him and his son with a science project that involved calculating the ballistic coefficient of a BB gun projectile. I provide dthis father-son duo with the required calculations (documented here) and the answer I obtained seemed reasonable. Continue reading →

Posted in Ballistics, Excel | Comments Off on BB Ballistic Coefficients

Optimized Piecewise Linear Model Using Excel

Posted on 23-December-2020 by mathscinotes

I was recently asked to create a piecewise linear model for a rather complex battery discharge curve, which is a type of task that I have performed dozens of times. I was told to perform this task in Excel because that is the only computation tool that this customer uses. I normally do this task in R because I like the segmented package, however, Excel does a very good job with the task, especially if you use the Solver add-in to "tune" the model. Continue reading →

Posted in Batteries, Excel | Comments Off on Optimized Piecewise Linear Model Using Excel

US WW2 Torpedo Production Chart Using Power Query

Posted on 12-December-2020 by mathscinotes

During my readings on the Pacific War, I often see the chart shown in Figure 1. I decided to do a bit of digging and find the source data for this chart in the hope of making a version of this chart that is a bit clearer and easier to use. Continue reading →

Posted in Excel, History Through Spreadsheets, Military History, Naval History | Comments Off on US WW2 Torpedo Production Chart Using Power Query

18% of American's Can Determine 52 Senators?

Posted on 6-December-2020 by mathscinotes

I was listening to a podcast this week where I heard James Carville state that "18% of American's can determine 52 senators." I thought this was an interesting quote that I could have the students I tutor verify using Excel and Power Query. All of the data is available online and the problem has a relatively short solution. Continue reading →

Posted in Civics Through Spreadsheets, Excel | 3 Comments

Willie Mosconi and How Pool is Like Life

Posted on 7-November-2020 by mathscinotes

I was talking with my neighbors yesterday about motivating students. They are both teachers at a local college and are finding it difficult to excite their students over Zoom.  While I am not in education, many of the companies I have worked for have struggled to motivate staff (local and remote). My employers would occasionally have occasionally brought in motivational speakers to try to fire up the workers, most of which were good but not great (Lou Holz was great). Continue reading →

Posted in Management, Personal | 4 Comments

Relative Cost of WW2 US Fighters

Posted on 19-October-2020 by mathscinotes

A reader of this blog mentioned in a comment that cost might be a big reason for the US Army Air Corps (USAAC) switchover to the P-51 from P-38s and P-47s. I thought I would put together a quick report on the relative cost of the three main USAAC fighters. The cost of these fighters by year was available in the Army Air Forces Statistical Digest (Hyperwar Site). The approach to Extracting, Transforming, and Loading (ETL) the data are the same as I used to determine the on-hand numbers of aircraft (link). For those who are interested in the details, my workbook is available here. Continue reading →

Posted in Excel, History Through Spreadsheets | 2 Comments

Lake Water Temperature Report Using Power Query and FILTERXML

Posted on 18-October-2020 by mathscinotes

I have a cabin in northern Minnesota on a small lake where I have been staying isolated from the rest of the US while COVID rages around me.  I track various lake metrics like height relative to sea level, clarity, and temperature.  I gather this information into a report that I send to the other folks who live on the lake. In this post, I show how I put together a chart of lake water temperature vs time using Excel and Power Query. I also demonstrate how to use the FILTERXML function to parse some rather messy data. I find myself using FILTERXML for data parsing more and more. Continue reading →

Posted in Cabin, Excel | 1 Comment

US Army Air Corp Fighters on Hand During WW2

Posted on 17-October-2020 by mathscinotes

Many years ago, at the start of my career, I worked with an excellent safety engineer who had served in WW2 as a fighter pilot in Europe with the US Army Air Corps (USAAC). You could tell that flying was the love of his life. Though we were working on naval weapons systems, our lunchtime talks often focused on his experiences flying aircraft during the war. His war service began in a P-47 (Figure 1) and his unit later transitioned to the P‑51 (Figure 2). Continue reading →

Posted in Excel, History Through Spreadsheets, Military History | 3 Comments

APR of Payday Loan

Posted on 5-October-2020 by mathscinotes

I watched a video (Figure 2) that shows Rep. Katie Porter (Figure 1) grilling the Director of the Consumer Financial Protection Bureau (CFPB) Kathy Kraninger in regards to the calculation of a payday loan's Annual Percentage Rate (APR). This blog post will show how to compute the APR for the payday loan example Rep. Porter attempts to get Ms. Kraninger to compute. I am not sure Ms. Kraninger knows exactly what APR is. The questioning is a bit uncomfortable because Ms. Kraninger is in no mood for a math exercise and Rep. Porter is not going to give up. Ms. Kraninger clearly is uncomfortable, but her discomfort is nothing compared to the discomfort experienced by a payday loan customer. Continue reading →

Posted in Financial | 2 Comments

US Government Management of Western Forest Lands

Posted on 19-September-2020 by mathscinotes

I am always looking for data analysis exercises for the young folks that I tutor online. While watching the coverage of the massive forest fires on the west coast of the US, I noticed that all the media were reporting that much of the forest land in these states are managed by the US government, which makes them responsible for managing these forests. I thought it would be a good exercise to show the students how to calculate the percentage of forest land that is managed by the US government. Continue reading →

Posted in Civics Through Spreadsheets, Excel | 3 Comments