Rule 2.b.line 3 The phrase should be a complete sentence starting with the wording "Supervisors will supply an attachment mechanism......."
The drop height is measured from the bottom of the bottle.
Folding the cord would not be considered a physical alteration. However, when folded, the cord would need to meet the elasticity test. Rule 3.c states "The cord may consist of more than one material...and more than one strand as long as it meets the elasticity test." Rule 3.c also defines the elasticity test "...while being suspended vertically, the bottom meter of the cord must stretch to at least 1.25 meters when a single mass is attached to this section and return to within 5 cm of its original length after the mass is removed."
The key ring is included in the meter for the elasticity test.
Approximately would be 3/8" to 1 1/8".
The 500 - 591 ml. bottle may be any shape. The total mass of the bottle, attachments & drop mass placed inside the bottle should be within the stated 50 - 300 gram limits.
No, dampening mechanisms violate the spirit of the problem.
Yes, it may include non-elastic sections. All cords will stretch. Some more than others. The rules define elasticity and as long as the cord meets the elasticity test and does not violate the spirit of the problem (allowing the drop mass to free fall) it is acceptable. Please note the last sentence in the definition of the elasticity test (3.c. ..."Self-limiting-brake" mechanisms such as a separate, parallel, non-elastic strand that "brakes" the fall of the mass with little to no rebound are not permitted.)
General rule #1 allows electronic items, while general rule #2 prohibits electronic devices capable of external communications. Hence, many calculators are allowed, but laptops are prohibited.
Any type of calculators are allowed as long as they are not capable of external communication per general rule #2.
Competitors will determine which end of the cord they wish to have tested for elasticity and attaching to the weight. Please note that the same end must be used for both activities.