Final answer:
In an elastic collision, the total momentum before the collision is equal to the total momentum after the collision. In this case, the angle between the velocity vectors of Mass A and Mass B after the collision is C. 90°.
Step-by-step explanation:
In an elastic collision, both momentum and kinetic energy are conserved. Let's consider the situation given in the question:
Mass A has a velocity of 15 m/s in the +x-direction, and Mass B has a velocity of 10 m/s in the -x-direction. After the collision, Mass A moves with a speed of 15 m/s in the -x-direction.
To find the angle between the velocity vectors of Mass A and Mass B after the collision, we can use the law of conservation of momentum, which states that the total momentum before the collision is equal to the total momentum after the collision.
The formula for momentum is:
momentum = mass × velocity
Since Mass A and Mass B have the same mass, the total momentum before the collision is zero (15 m/s × m - 10 m/s × m = 0). Therefore, the total momentum after the collision must also be zero.
Since the momentum of Mass A is in the negative x-direction after the collision, the momentum of Mass B must be in the positive x-direction in order for the total momentum to be zero. So, the angle between the velocity vectors of Mass A and Mass B after the collision is 90° (perpendicular).