True or False? 6. In each collision the kinetic energies of the colliding bodies definitely change. 7. When two spheres with equal masses collide centrally and elastically, the spheres exchange their kinetic energies. 8. In each impact, the momentum of the colliding body system is marginally the same before and immediately after the impact, but varies during the impact. 9. In each central and elastic impact of two bodies the velocities of the bodies before and after the impact are always in the same line. 10. In any two-body collision, the momentum changes of the colliding bodies are opposite.