Final answer:
The question pertains to a completely inelastic collision where two bodies with equal mass and equal initial speed collide and then move together. It involves an understanding of conservation of momentum and how vector addition applies in two dimensions, although the exact angle cannot be determined without additional information on the directions of the initial velocities.
Step-by-step explanation:
The question deals with a completely inelastic collision in two dimensions, where two bodies of the same mass and initial speed collide and move together afterwards. When we consider conservation of momentum for inelastic collisions, momentum is conserved but kinetic energy is not. Because they move together with a final speed that is half of their initial speed, the angle of the combined velocity vector relative to the initial direction of one of the bodies depends on the initial direction of both bodies.
In a two-dimensional collision where the bodies have equal mass and move towards each other at equal speeds, we can analyze the situation by breaking down the velocities into components. Since the masses and speeds are equal, their momentum vectors would be of equal magnitude but in opposite directions. When they collide and move together with half the initial speed, they do so in a direction that is the average of their initial directions, assuming the collision is symmetrical.
To find the angle between the initial velocities of the two bodies, we would need to apply vector addition and trigonometry; however, without specific directional information, we cannot calculate an exact angle.