Physics Cup – TalTech 2024 – Problem 1

By Jaan Kalda (TalTech).

The video below shows a solid cylinder falling into water in slow motion. Determine the density of the cylinder. You are allowed to take measurements from the video frames.

When you submit your answer-only solution, send the formula for your final answer, and explain which measurements will be taken from the video. At this stage, you don’t yet need to perform the measurements – you can take your time to get good measurements and send the numerical answer only with your final solution (as always, within 48 hours from the initial submission).

For making better measurements you are advised to download the video and open it with a video viewer that allows frame-by-frame navigation (e.g. MPC-HC with Ctrl-> and Ctrl<- for frame-by-frame navigation, or VLC with “e” to go to the next frame). Don’t expect your answer to be very precise due to the inaccuracy of the measurements.

Please submit the solution of this problem via e-mail to First intermediate results will be published on 22nd October, 13:00 GMT. After the publication of the first hint, the base score is reduced to 0.9 pts. For full regulations, see the “Participate” tab.