December 3, 2018

Three parts

  1. Experiment
    • If possible, we will do an experiment
    • You need your cellphone’s camera
  2. Genomic databases
  3. Planets

Free fall

  • I will drop an object in front of the class
  • The screen will show a timer
  • You must record the experiment with your cellphone
  • In your computer, open a new text file and write the experimental data
    • three columns: seconds, position, and replica
    • one row for each time the object crosses a mark
  • Send your text file to

Example videos

Second part

Genomic databases

Every time a researcher publishes a paper about DNA sequencing, all the sequences are uploaded to several databases.

One of these databases is

It contains all DNA reads made with New Generation Sequencers

We want to understand how fast this database is growing


The plot must look like this

Database growth

  • The growth of databases is usually modeled as a semi-log linear model.
  • Build a semi-log model and find
    • what is the factor of growth per day?
    • What will be the database size two years after the last entry in your table?
  • write your code and comments in the same Rmarkdown file

Third part


The file planets.txt contains the astronomical data for the planets in our solar system. The columns are:

  • Name of the planet,
  • Diameter in km,
  • Distance to the sun in km,
  • AU: distance to the sun in astronomical units, and
  • Period of the orbits in days

We want to find the relationship between Period and Distance


  • Download the file planets.txt
  • In the same Rmarkdown document as the previous question, create a new section
  • write the code to read the file into your document
  • Draw three plots
    • One using normal scales
    • One using semi-log scales
    • One using log-log scales


  • Based on the 3 plots, decide which is the best approach to use a linear model. Explain why you made that decision.
  • Build the model and show the coefficients
  • Compare your result with Kepler’s third law


  • Looking at the log-log plot, do you think that there is something missing?
  • Find the Distance and Period for the “missing planet” between Mars and Jupiter


You should send two files to

  • The text file with the first part
  • The Rmarkdown file with the second and third part

You can send the files in a single email or in two separated ones

Put your student number in the subject