3.4 Working with models

Example: Free fall

Course element	Work	Learning activiteity
Validation Evaluation and assessment	Evaluation of the applicability of the model on the basis of outcomes, expectations and (measured) data Summary of the outcomes and the used procedures, and discussion in class	Discussion in class: What have you learned? What can you do with it?

To validate the model of free fall (without friction), students can compare the computed results of the model with:

1.  the analytical description of a uniformly accelerated falling motion:¹
   $$\begin{array}{l}a=-g\\ v=a\cdot t\\ y=y(0)+\frac{1}{2}a\cdot t^2\end{array}$$
2. the measured data from the experiment of falling motion, in which air friction possibly plays a role;
3. the results of the model for other step sizes.

Students try to estimate the accuracy and reliability of the model and the data, and to what extent the step size and the air resistance make a difference. This can be a first step towards modifying the model to describe situations with air resistance.² See 4.1 Force and motion for some elaborated computer models.