From an instrument that has no recoil device, the shooting was carried out in a horizontal direction. When the gun was secured, the projectile flew at a speed of 600 m / s, and when the gun was given the freedom to roll back, a shell flew at a speed of 580m / s otnostielno Earth. How fast rollback in this instrument?

Detailed solution shorthand terms, formulas, laws used in the decision, the withdrawal of the calculation formula and the response.