Pre-build: Smartphone Elevator
Last updated: February 7, 2021. Download the pdf version here.
Judges: Dr. Andrzej Kotlicki (kotlicki@phas.ubc.ca) and Dr. Valery Milner (vmilner@phas.ubc.ca). Any questions about this activity should be directed to the activity judges.
The deadline for submission is 11:59 pm on Tuesday, March 1st, 2022. Instructions for submitting materials online will be announced soon.
Main objective
Your team’s objective is to build an apparatus that will transport a typical smartphone from the surface of a table, 1 m above the floor level, to the floor in the shortest possible time and with the smallest possible peak acceleration.
Apparatus construction
The only energy used in the whole process should be the potential gravitational energy of the phone or any other parts of the apparatus. This energy can be converted during the process to other forms of mechanical energy.
The apparatus may be built out of any non-hazardous materials. Any apparatus that represents a hazard to the operator or bystanders will be disqualified. Contact the judges should you have any concern about the material or the design principles.
The apparatus must not exceed the dimensions of 2 m x 2 m x 2 m.
The apparatus may incorporate pre-manufactured objects.
Judges have the final decision on determining whether the apparatus is compliant with these rules.
Any mechanical motion of the constructed apparatus, including the transportation of the smartphone from the table to the floor, must be started by cutting a thread.
The position of the smartphone inside the built apparatus should be not higher than 2cm from the surface level on which the apparatus resides, both at the beginning and at the end of the transportation process.
Measurement
The smartphone should be pre-loaded with the free PhyPhox app (Links to an external site.), and will be the only measuring device used in this pre-build activity. The app will record acceleration during the process of transporting the phone using the “Acceleration (without g)” function.
—At the beginning of the transportation process:
* The smartphone should lay flat on the table or inside the built apparatus so that the whole surface of the phone is above the surface of the table (i.e. not sticking out beyond the table’s edges). The transporting apparatus, on the other hand, may extend beyond the edges of the table.
* The smartphone must be oriented face-up with its screen reachable by the operator, who should be able to start the PhyPhox app without moving the phone from its initial position. You can also start the app remotely with your computer without touching the smartphone using the remote function of the PhyPhox.
* The PhyPhox app must be started approximately 10 seconds prior to triggering the transportation process (which is done by cutting a piece of thread). In other words, your recorded data must start with approximately 10 seconds (plus/minus a couple of seconds) of “quiet time” when nothing moves.
—At the end of the process:
* The smartphone should again be oriented face-up and be reachable by the operator, who will stop the PhyPhox data collection without moving the smartphone.
* The data collection should be stopped approximately 10 seconds (again, plus/minus a couple of seconds) after the smartphone comes to rest.
Scoring
The score will be the product of two numbers: the transportation time, during which the phone was moving, and the maximum absolute value of the recorded acceleration to the power of three.
Score = t * a3, where t is measured in seconds and a in m/s2.
The apparatus that produces the smallest score will win.
The transportation time will be determined as the time between two events: (1) the moment the absolute value of the recorded acceleration at the end of the initial “quiet period” (of roughly 10 seconds) increases above a threshold of either 0.1m/s2 or 1% of the maximum recorded acceleration, whichever is smaller; and (2) the moment the absolute value of the recorded acceleration at the beginning of the final “quiet period” (when the phone is resting within 2 cm from the floor level) decreases below a threshold of either 0.1m/s2 or 1% of the maximum recorded acceleration, whichever is smaller.
The maximum absolute value of the recorded acceleration will be extracted from the submitted PhyPhox data file. The two spikes in acceleration, one at the very beginning of the record and one at the very end – both due to the tapping on the phone’s screen for turning the app on and off, will be disregarded.
Data submission format
Each team must submit one Excel file named according to the following template ‘SCHOOL_NAME.xls’ (e.g., ‘University_Hill.xls’ or ‘Lord_Byng.xls ’).
The file should be generated within the PhyPhox app by pressing on the menu sign and choosing “Export Data” and then “Excel” format. The data file must not be modified in any way other than changing its name according to the template described above. Any suspicion that the contents of the file were modified will result in disqualifying the team!
Each team must also submit a video of the transport process during which the data in the submitted Excel file was generated. Instructions for submitting videos will be announced soon.
Demonstration
Selected teams will be requested by judges to explain and demonstrate how their apparatus works, and generate new data from the particular demonstration, on the day of the Physics Olympics event (March 5, 2022). The team will have to immediately transmit new data to the judges after the demonstration. Teams should monitor their emails and Canvas on or before March 5 in case judges contact them.