IYPT 1994, Задачи на турнира — Задача 14. Magnetic friction

7th IYPT (1994)

Условие

To investigate the phenomenon described in the problem 3 we suggest to create the device containing the following elements:

• a copper plate (or a set of plates) 0.3 to 15 mm thick. The length and the width of the plate may be chosen according to one’s convenience, but they should be large enough to avoid the effect of the boundaries;
• a cylindrical electromagnet with a flat butt-end;
• a device providing free motion of the flat butt-end of the electric magnet over the horizontal surface of the copper plate. It is very important that the gap between the magnet and the plate is small as possible and constant everywhere;
• the push providing the uniform motion of the magnet at a given velocity over the plate surface.

Introduce the following notation: $T$ — the push (and the force of magnetic friction), $v$ — the velocity of the magnet, $h$ — the thickness of the plate. Investigate and determine experimentally the dependence of $T$ on $h$ at $v=\mathrm{const}$ for several values of $v$.

Решение

Оригинал в Архива: 1994.txt