weak vacuum that holds the marble in place until the pendulum hits the stop-bar. The lengths and angles shown here are used to estimate the velocity and angle of the marble impact on the sand. See Table \[tab:pend\] for a list of quantities and Table \[tab:nomen\] for nomenclature. \[fig:pend\] ](pend.png){width="3.4in"}

![Side-view illustrations of our pendulum based marble launcher. The pendulum is dropped from a height $h$, setting the velocity of impact. The pendulum swing is stopped by a stop-bar at an angle $\theta_{sb}$ that sets the angle of impact. The marble is ejected from its holder when the pendulum is stopped and then hits the sand. The red bulb is used to apply a weak vacuum that holds the marble in place until the pendulum hits the stop-bar. The lengths and angles shown here are used to estimate the velocity and angle of the marble impact on the sand. See Table \[tab:pend\] for a list of quantities and Table \[tab:nomen\] for nomenclature. \[fig:pend\] ](pend2.png){width="3.4in"}

![Photograph of the experimental setup. The high speed camera and white light are on the left, whereas the blue LEDs are on the right. The sand box is just above the floor. \[fig:setup\] ](setup_small.jpg){width="3.4in"}

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