Make use of the fact that if the boy runs always on the verge of slipping, the length of the curve drawn in the v_x-v_y plane is proportional to the running time: a fixed running time corresponds to a fixed curve length.

*Please submit the solution to this problem via e-mail to physcs.cup@gmail.com.** *The next hint for the Problem 2 will be published at **13:00 GMT, 16th January 2022**, together with the next updates of the intermediate results.* *