Task id17023

Here is another paradox of the theory of relativity. Let the spring be located perpendicular to the direction of the speed of the reference frame. Under the influence of force Fo, the spring stretched to a length L0=Fo/k. As is known, when moving to another reference system, the transverse dimensions do not change, therefore, L=L0. Doesn't this contradict the fact that the transverse force changes according to the law F==F0·sqrt(1-v2/c2).