Figure 2 shows that the speed increases with time and approaches a terminal value. The expressions from Eqs. (4) and (10) are fitted to the black curve in Fig. 2. Our students use the software package Graphical Analysis from Vernier
Software.13 Also Eq. (11) was used to fit the data on Fig. 1 [in principle also Eq. (5), but this is indistinguishable from Eq. (11) and is omitted for clarity]. Note the highest speed actually reached during the descent is slightly lower than the fitted “terminal speed”: to reach the latter, a longer runway would be needed. But it is not so easy to find a long smooth stretch with a constant slope angle