This topic is for posting questions (and answers) to the various Physics Olympics events. NOTE: THE DEADLINE TO RECEIVE A RESPONSE IS NOVEMBER 30. AFTER THAT, YOU MAY VIEW THE POSTS, BUT WILL NOT RECEIVE A RESPONSE FROM THE EVENT PLANNERS.
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Collapsing Tower question -- previously posted by Daniel Kaplan on 9-27-2017:
Last time that we ran this event we were allow to drill a hole in the one domino that we pull during the event. The purpose was to allow for a better attachment to the string.
- Are we allowed to do this?
- Are we allowed to modify any of the other dominos?
Collapsing Tower Answer -- previously posted by John Valente on 10-02-2017:
Allowing a hole to be drilled through a domino for the purpose of attaching a pulling string is within the spirit of the rules so is permissible. The hole should fit the string being use so should not appreciably alter the mass of the domino.
The remaining dominoes may not be altered.
Greatest Acceleration Racer Question, posted by Daniel Kaplan on 10-13-2017:
I am not clear on what is meant by greatest acceleration. We can certainly not assume that the acceleration is constant. Is it the greatest average acceleration of the length interval or the greatest measurable instantaneous acceleration? If it is the greatest average acceleration, is it averaged by time or by distance?
Greatest Acceleration Racer Answer, Posted by John Valente on 10-14-2017:
The performance of the project in the Greatest Acceleration Racer will be based upon the average acceleration of the project within the specified dimensions of the course (0.25 m through 1.25 m). A motion detector will be used to generate x-t and v-t graphs for each run. Once a run is complete, the graphing tools can be used to identify and display the numeric values for points of interest. The time at which the racer has moved 0.25 m and 1.25 m from the motion sensor will be determined from the x-t graph. These time values will be located along the v-t graph (as close as possible in some cases) and the corresponding velocity values will be obtained. A sample run for a wind-up toy is shown below. However the length for this trial was only from 0.25 m to 0.60 m. Four data points have been identified - time at position 0.25 m, the corresponding velocity at the closest possible time to the position value, the time at the finish line (0.6 m for my sample run), and the corresponding velocity for the previously mentioned position value.
To see the data referred to, click on link below. Can't post it here in the forum due to file size limits.
Here's a link to the graph/data
With this data, the average acceleration value may now be determined. Since we are only interested in the greatest average acceleration, we can determine it using change in velocity divided by the change in time. This data can be extracted from the graph displayed above The calculation can then be performed with the aid of a calculator or in a spreadsheet. On competition day, the latter will most likely be used as it will be able to perform the calculation as data is entered. This approach would apply to all racers regardless of whether the vehicle moved with a constant acceleration or not.
From Dave Bandel, Judge of this event
Greatest Acceleration Racer - So I see that a motion detector will be used to analyze the acceleration of the racer. What course will the racers run on? Can we use the 2.2 m long pasco aluminum tracks to keep the racers in the line of the motion detector or will the racers run along the school floors or desks? Are we definitely not using photogates? Are there any maximum dimensions for the racer?
Answer from David Bandel/John Valente. To enable the design not to be too restrictive, the course will be along the school floor-no tracts. We will not us photogates. The rules do not state dimensions. Since the racer can not be powered by more than two mousetraps and the goal is to have the greatest acceleration, these restrictions would limit the size of the racer.
Coffee Can Racer -- suggestion
There is an app for tablets/phones called "Clinometer" which will easily measure the angle that the ramp should be set at (10 degrees).
Thanks for everyone's questions and input.
Quick question about the greatest acceleration racer event. The rules state that the mouse trap can not be altered with the exception of mounting and synchronization. Would removing the mouse trap bar to attach a wire hanger be out of bounds?