A baseball is dropped on top of a basketball. The basketball hits the ground, rebounds with a speed of 4.0 \mathrm{~m} / \mathrm{s}, and collides with the baseball as it is moving downward at 4.0 \mathrm{~m} / \mathrm{s}. After the collision, the baseball moves upward as shown in the figure and the basketball is instantaneously at rest right after the collision. The mass of the baseball is 0.2 \mathrm{~kg} and the mass of the basketball is 0.5 \mathrm{~kg}. Ignore air resistance and ignore any changes in velocities due to gravity during the very short collision times. The speed of the baseball right after colliding with the upward moving basketball is
Answer Choices
A. 4.0 \mathrm{~m} / \mathrm{s}
B. 6.0 \mathrm{~m} / \mathrm{s}
C. 8.0 \mathrm{~m} / \mathrm{s}
D. 12.0 \mathrm{~m} / \mathrm{s}
E. 16.0 \mathrm{~m} / \mathrm{s}
