A spaceship of mass  $m_0$ moves in the absence of external forces with a constant velocity  $v_0.$  To change the motion direction a jet engine is switched on. It starts ejecting a gas jet with velocity relative to space ship being u such that u is constant and always directed at right angles to   the spaceship motion. The engine is shut down when the mass of the spaceship decreases to $\frac{m_0}{7.4}.$   Find the angle in radians by which the motion direction of the spaceship will deviate due to the jet engine operation.Use the value  $\frac{u}{v_0}=1.$