The accompanying figure shows the plot of distance fallen versus time for an object that fell from the lunar landing module a distance 80 $\mathrm{m}$ to the surface of the moon.
\begin{equation}
\begin{array}{l}{\text { a. Estimate the slopes of the secant lines } P Q_{1}, P Q_{2}, P Q_{3}, \text { and }} \\ {P Q_{4}, \text { arranging them in a table like the one in Figure } 2.6 \text { . }} \\ {\text { b. About how fast was the object going when it hit the surface? }}\end{array}
\end{equation}