Tutorials (Pendulum experiment)

Video Tutorial for the analysis of the oscillations with Tracker (in Italian).

Short video showing how to evaluate uncertainties through differentiation (in Italian).

Frequently Asked Questions.

• What precautions should I take to minimise relative errors?

1. Build a pendulum with a length as big as possible (according to the available spaces you have in your room). This will reduce the relative error on the length measurement. In addition a bigger L will provide a longer period T: again you will reduce relative errors on the time duration measurements.
2. Position yourself beside the trajectory described by the pendulum at one of the two motion inversion points. Each time the pendulum returns at that point, an oscillation will have been completed. At that point, moreover, the pendulum will have zero speed so the measurement of the duration of the oscillations will be more accurate.
3. Make the trajectory of the body occupy the biggest part of the field of view of your video shoot. In this way the error in evaluating the position of the body will be less important. (If the trajectory of the body is spread over a lot of pixels an error of few pixels in evaluating its position is less important).

• (TracKer) What do I do if, clicking on ‘View’ >> ‘Data Tool (Analyse)’, experimental data do not appear in the numerical data columns and in the plot? Go in the main Tracker window, put the mouse cursor in the region in which you see the columns with numerical data (on the right, below the the plot x(t) ), right-click and a drop down menu will appear, select the option “analyse data”.
• (Tracker) If the sine curve x(t) I get from the mass tracking is not centred in x = 0? Try to achieve a better positioning of the origin of the x axis (along with the pendulum moves): the origin should be in the centre of mass of the body in its vertical equilibrium position.
• (Adhesive tape) Is the fixing of the sewing thread ends with adhesive tape stable? The adhesive tape has to be placed carefully so that it holds firmly the thread well. You have to take into account that over a long time the adhesive tape may allow a small sliding of the sewing thread, due to the weight of the mass. If you make a measure of the pendulum length and you measure the oscillations a long time after you will be likely working with a longer pendulum than you expect. Therefore it is a good practice to frequently monitor the pendulum length.