Author Archives: mathscinotes

Pejsa's Projectile Drop Versus Distance Formula (Part 2 of 3)

Posted on 7-May-2015 by mathscinotes

In our previous post, we developed an expression for y' (=dy/dx, Newton's notation) expressed as differential equation in terms of x. We will now solve this equation through the use of an integrating factor. Having solved for y' in terms of x, we can integrate that expression to obtain y(x). Continue reading →

Posted in Ballistics | 11 Comments

Pejsa's Projectile Drop Versus Distance Formula (Part 1 of 3)

Posted on 6-May-2015 by mathscinotes

I recently have had a number of readers ask me to continue my review of Pejsa's "Modern Practical Ballistics". The last major topic I have left to cover is his formula for the drop of a horizontally‑fired projectile as a function of distance. My plan is to derive the formula and present an example of its use. The derivation is not difficult, but it is a bit long and I will divide my presentation into a couple of posts. Continue reading →

Posted in Ballistics | 13 Comments

I Must Be Old, All the Bugs Sound Familiar ...

Posted on 4-May-2015 by mathscinotes

I was reading an article this morning about a bug discovered in Boeing's 787 software that will occur after 248 days of continuous operation. The moment I read "248 days", I let out a sigh – I have seen that number before. Continue reading →

Posted in software | 2 Comments

Good Example of the Economy of Scale

Posted on 28-April-2015 by mathscinotes

Yesterday, I saw an interesting article in the Journal of Light Construction (JLC) that does an excellent job of showing how the per-square foot cost of a deck construction drops as the total area of the deck increases (Figure 1). I found this interesting because I am going to have a structure built on my lake property in northern Minnesota. I thought this data would provide a good illustration of how I use Mathcad generate product cost models. Continue reading →

Posted in Construction, Management | Comments Off on Good Example of the Economy of Scale

Statistics Example from World War 2

Posted on 22-April-2015 by mathscinotes

I recently finished a course on Bayesian analysis from Statistics.com and I have been looking for application examples that will provide me with some experience using these methods. I like to compare the Bayesian solutions with the standard solutions (usually called Frequentist). Continue reading →

Posted in Statistics | Comments Off on Statistics Example from World War 2

Banana Equivalent Dose

Posted on 17-April-2015 by mathscinotes

I recently have been reading quite a bit about the hazards of traveling to Mars – one of the major hazards is radiation. This Mars reading has driven me to write a number of posts that look at the effects of radiation exposure in our daily lives here on Earth. Continue reading →

Posted in General Science, Geometry | 2 Comments

Candidate for the Dumbest Idea I Have Heard

Posted on 16-April-2015 by mathscinotes

My coworkers and I often discuss our home remodeling/repair adventures. This morning, a coworker described how a neighbor in his home town used a rifle to solve a common plumbing problem. I do not condone this approach and I am appalled at every possible level that someone would even try it. Continue reading →

Posted in Construction, Humor | 2 Comments

Another Real Life Savings Example

Posted on 15-April-2015 by mathscinotes

I really enjoy managing my own investments and I draw inspiration from the stories of other amateur investors who have been successful at saving and investing. My working class upbringing did not provide me with any exposure to investing in my youth, so I really did not start actively investing until I was in my late 30s – now I wish I would have started about ten years earlier. Continue reading →

Posted in Financial | Comments Off on Another Real Life Savings Example

Geometric Table

Posted on 14-April-2015 by mathscinotes

I am always looking for interesting construction projects. I don't necessarily plan to build them for myself, but I do often turn to these project for inspiration. I usually store them on Pinterest. Continue reading →

Posted in Construction | Comments Off on Geometric Table

Computing a Ship's Course from Four Bearings

Posted on 13-April-2015 by mathscinotes

I have made no secret of my love for all things nautical – even my game playing has a nautical theme. When I have spare time, I like to play Silent Hunter 3 or 4. While these are older versions of the Silent Hunter franchise, I still enjoy playing them very much. What brings me back to Silent Hunter is how easily I can vary the level of realism to suite my gaming needs. Continue reading →

Posted in Military History, Navigation | 5 Comments