tube in order to hold the sand, yet allow the air to flow through the frit into the sand.
Sand is put into the glass tube that are sphere glass beads sizes of 63-106 m diameter.
Air is pushed through the frit from a flow meter through a heater at 205 F to fluidize the
sand at certain flow rates. The heater is used to drive off water vapor in order to prevent
sticking or clumping. For example, in sandcastles, wet sand seems to use water as glue to
hold the sand together, and as it dries the sand collapses into its many small pieces. This
is why heating the sand is important. A ball is attached to a nylon wire (.01 in thick) that
is then attached to a force transducer on a translation stage. The translation stage is
connected to a stepper motor with a flexible shaft. The force transducer is attached to a
Stanford Research Systems lock-in amplifier model SR830 DSP. The lock-in amplifier
and motor controller are both connected to a computer that is programmed using
LabVIEW. LabVIEW is programmed to move the translation stage up and down with
certain velocities and receive data from the force transducer, which measures the force
needed to drag the ball through the sand