Question

Your group has been asked to examine collisions in which the pucks stick together after the collision. To get the pucks to stick together, your group has wrapped the circumference of each puck with velcro (the regulation puck has the velcro hooks and the practice puck has the velcro loops) with the hooks or loops outward in each case. To get consistent puck speeds before the collision, your group has constructed a pair of rubber-band launchers, in which a very strong rubber band is stretched tightly between two posts and then used like a slingshot. A few trials are sufficient to determine that these launchers, if used carefully, can launch the pucks with predictable speeds and with essentially no spin?

Answer 1

If necessary, readjust the f-stop of the CCD camera until only the LED’s from the pucks

are visible. You may find that a vertical stripe appears associated with the LED. This

is called streaking or ‘blooming’ and is a limitation of CCD technology in the presence of

localized bright spots. Some amount of streaking is acceptable, and can be compensated for

later in the computer analysis.

Once the exposure level of the camera has been set you should capture a ‘dark frame’.

For this, first remove all pucks, hands, etc., from the air table and click on the box to the

right of Background Frame. The dark frame can later be subtracted from your images of

collisions to suppress any constant background such as the edge of the table.