Mathematical and Physical Journal
for High Schools
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Problem P. 4502. (January 2013)

P. 4502. A disc is given a push and slides on the top a horizontal table. It stops in a distance of L0. When the disc is placed to the rim of the table, which is at a height of H, and is given the same initial speed it reaches the ground at a distance of d from the table.

a) What is the kinetic frictional coefficient between the table and the disc?

b) At what distance from the table will the disc reach the ground if initially it is not exactly at the rim of the table but at a distance of L from the rim, (L<L0), the disc is given the same initial speed, and slides towards the rim of the table.

(Data: H=L0=d=0.8 m; L=0.6 m.)

(4 pont)

Deadline expired on February 11, 2013.

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

Megoldásvázlat. \(\displaystyle a)\)

\(\displaystyle \mu=\frac{d^2}{4HL_{0}}=0{,}25.\)

\(\displaystyle b)\)

\(\displaystyle d'=d\sqrt{1-\frac{L}{L_0}}=0{,}4~\rm m.\)


157 students sent a solution.
4 points:124 students.
3 points:9 students.
2 points:13 students.
1 point:7 students.
0 point:4 students.

Problems in Physics of KöMaL, January 2013