Abstract: The 12th problem of 2019 China Undergraduate Physics Tournament ( CUPT) was to study the de- celeration of a gyroscope made of nonferromagnetic conductor materials when placed in a magnetic field. There is no specific parameter to be qualified in the question，which is difficult to be solved comprehensively and uniformly by Maxwell’s equation. Starting from the infinite long conductor cylindrical model in this paper，the formulae of elec- tromagnetic resistance moment depends on magnetic induction strength，angular velocity，conductivity，and other parameters are obtained. The deriving process of these formulae is going under the condition that the direction

of the magnetic field is vertical or parallel to the gyroscope’s shaft with reasonable

approximation. Then the general rela- tion of gyroscope deceleration damping coefficient is given

when the direction of the magnetic field is relative to any

direction of the gyroscope’s shaft with the rationality verified through the dimensional analysis.

In the experimental part，an experimental facility driven by a DC motor is designed，and the

analysis of measurement data shows that the formulae of the electromagnetic resistance moment

obtained from the basic model can describe the actual gyro- scope deceleration process more

accurately.

Key words: IYPT, CUPT, gyroscope, magnetic field