Mathematical and Physical Journal
for High Schools
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Problem P. 5046. (September 2018)

P. 5046. A board of mass \(\displaystyle M\) was fixed symmetrically as shown in the figure. The masses of the fixed pulleys and the ropes, as well as friction in the shaft are negligible. (The objects of mass \(\displaystyle m\) are not glued to the board of mass \(\displaystyle M\).) At what \(\displaystyle m/M\) ratio will the system be in equilibrium?

(3 pont)

Deadline expired on October 10, 2018.


Sorry, the solution is available only in Hungarian. Google translation

Megoldás. Ha \(\displaystyle \frac{m}{M} \ge \frac12\), a rendszer egyensúlyban van. Ilyenkor a deszka nem tud lesüllyedni, hiszen akkor a rendszer helyzeti energiája növekedne (vagy változatlan maradna). A deszka felemelkedni csak a rajta lévő testekkel együtt tudna, ez pedig ugyancsak a helyzeti energia növekedésével járna, tehát nem valósulhat meg.


Statistics:

107 students sent a solution.
3 points:64 students.
2 points:33 students.
1 point:3 students.
Unfair, not evaluated:6 solutionss.
Not shown because of missing birth date or parental permission:1 solutions.

Problems in Physics of KöMaL, September 2018