In a recent paper by C. Mungan [Phys. Teach. 56, 298 (2018)], where a falling chain is analyzed, we can see the following statements in the online appendix with reference to two papers,1,2 where I am the first author:

(1)

where they put u = v.

These statements deserve some remarks.

AAPT members receive access to The Physics Teacher and the American Journal of Physics as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.