A system of inertia 0. The system is at rest on a horizontal low-friction track.

A system of inertia 0.57 kg consists of a spring gun attached to a cart. The system is at rest on a horizontal low-friction track. A 0.050-kgprojectile is loaded into the gun, then launched at an angle of 40∘with respect to the horizontal plane.

With what speed does the cart recoil if the projectile rises 2.1 m