## Zip-A-Dee-Doo-Dah: Cable car hook orientation.

Q: I know we can not turn or move the hooks that glide along the zip line, but what about the hook from which the cable car hangs?  Can we rotate that hook 90 degrees if it better suits our attachment method to get the cable car to hang in the orientation we want?

A: You may turn the hook from which the cable car hangs if it better suits your design.

## Zip-A-Dee-Doo-Dah: Velocity Calculation

Q: For the velocity calculation, are we using the distance of the Zipline (the hypoteneuse of the triangle) and the base distance?

A: Yes, we are using the distance of the zipline (hypotenuse of the triangle). For the velocity calculation on the test (for 4th & 5th graders), we will provide the distance (in meters) and run time, and the students will be expected to calculate the average velocity. The kids are not expected to know trigonometry (e.g., they will not have to calculate the hypotenuse given the width / height of the triangle).

We will provide all the triangle dimensions for the physical zipline setup (in both meters and feet), but the kids will not be expected to do any calculations in the building phase.

## Zip-a-dee-doo-dah: Photogates not activating

Q: If the photogates do not activate/record for their run during the event, are they allowed to rerun it?

A:  Yes, they can re-run the cable car if the photogates do not activate (this won’t count as an additional trial).

Q: Can more than one student load the harness on the line? For example, can one hold the harness while the other directs and stabilizes the cargo?

A. Only one student can load the harness and cargo on the zipline at one time. Teams can switch students for each of the 3 trials.

## Zip-a-dee-doo-dah: Ping Pong Ball

Q: Can you modify the ping pong ball?

A:  No modifications can be made to the ping pong ball; the students can only modify their cable cars.

Q: Clarification of the ping pong ball placement in the cargo.

A: The event description states: “Each team will have no longer than 30 seconds to place the ping-pong ball in the cable car and attach their cable car to the harness on the zipline.” This means that the ping pong ball “passenger” cannot be glued, taped or encased in the cable car in such a way that it can not be removed and reseated in the cable car within that 30 sec period. The goal should be to build a cable car that you can place the ping pong ball into, not to build around the ping pong ball.