对验证相对论中动量和动能关系的经典实验重新做了实验研究，发现改变磁场强度后该实验的结果并不符合相对论预言的动量和动能关系。根据实验结果，指出了狭义相对论的运动方程中，物体运动时受力（理论值）不变假定是错误的，并提出物体的受力（理论值）应随着运动速度的增加而减小。通过实验，还发现原来实验中对能量的定标偏高。

An experimental study on the classical experiment that verifies the momentum-energy relation in the special relativity theory is carried out and it is found that when magnetic intensity varies the experiment results do not confirm to the prediction of the special relativity. By analyzing the results, the paper points out that the postulate of special relativity on the invariation of the force acted on a moving electron is wrong, and further proposes that the Lorentz force (theoretically) acted on the moving electron should decrease as the velocity of electron increases.