Tag excel

Basics: Numerical Calculations

rhettallain 4 Comments

**Pre Reqs:** [Kinematics](http://blog.dotphys.net/2008/09/basics-kinematics/), [Momentum Principle](http://blog.dotphys.net/2008/10/basics-forces-and-the-momentum-principle/)

What are “numerical calculations”? Why are they in the “basics”? I will give you really brief answer and then a more detailed answer. Numerical calculations (also called many other things – like computational physics) takes a problem and breaks into a WHOLE bunch of smaller easier problems. This is great for computers ([or a whole bunch of 8th graders](http://blog.dotphys.net/2008/09/computational-physics-and-a-group-of-1000-8th-graders/)) because computers don’t mind doing lots of little problems. Why are they “basic”? Well, most text would say they are not basic. I disagree. I think this is a legitimate method for solving problems. In particular, this is a great way of solving problems that can not be solved analytically (meaning solving one hard problem).

**Numerical Calculations are Theoretical Calculations**

Let me just get this out of the way. Numerical calculations and analytical calculations are really in the same “class”. Often people will lump numerical in with “computational experiment” but that is a really bad thing to do. Some others will claim that there are three different “paths” to discover stuff in science: theory, experiment, and simulations. Simulations are the same thing as numerical calculations which are the same as theory. ([I wrote a letter about this in the American Journal of Physics](http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=AJPIAS000076000009000797000001&idtype=cvips&gifs=yes))

**Example Problem**

Let me start with a problem that can be solved analytically. Suppose I have a ball of mass 0.5 kg and I throw this straight up with a speed of 10 m/s. How high will it go?

Continue reading “Basics: Numerical Calculations” →

Basics: Making graphs with kinematics stuff part II

rhettallain 6 Comments

**pre-reqs**: [kinematics](http://blog.dotphys.net/2008/09/basics-kinematics/) *I don’t think you need [part I of this](http://blog.dotphys.net/2008/09/basics-making-graphs-with-kinematics-stuff/) if you don’t want*

So, you still want to make a graph with that kinematics data? You think that graphs on paper are too barbaric? Well, if you are ready, you can use a spreadsheet. But be careful. If you don’t know what you are doing, you can cause some damage (much like flying a 747 after reading a blog about it). Speadsheets allow you to do a couple of things.

  • make pretty graphs
  • fit mathematical functions to data

Of course they actually do much more – but you need [“clippy”](http://en.wikipedia.org/wiki/Clippy) to help you with that.

First, what software do you use? I think most people will immediately go for Microsoft Excel. I have to admit, this is what I use because I am so familiar with it. Many people already have this also. Truthfully, it is a good spreadsheet program (but not perfect). There are some free alternatives:

  • Open Office – I use the Mac OS X variant Neo Office
  • Online spreadsheet like Zoho) or Google Docs. Both of these are fairly useable.
  • Other – like Apple’s spreadsheet or other non-free stuff.
  • A final excellent option is Vernier’s Logger Pro. Although it is not free (nor perfect) it is not too expensive and can be covered by a school site license

For this tutorial, I will show explicitly how to make graphs using MS Excel. I was going to use open office, but in order to fit a polynomial to data, you have to do some more serious stuff. The basic idea is the same no matter what you use.

Continue reading “Basics: Making graphs with kinematics stuff part II” →