单项选择题
A
head-on, elastic collision occurs between two billiard balls of equal
mass. If a red ball is traveling to the right with speed vand
a blue ball is traveling to the left with speed 3vbefore
the collision, what statement is true concerning their velocities
subsequent to the collision? Neglect any effects of spin. ( )
A．The
red ball travels to the left with speed v,
while the blue ball travels to the right with speed 3v.
B．The
red ball travels to the left with speed v,
while the blue ball continues to move to the left with a speed 2v.
C．The
red ball travels to the left with speed 3v,
while the blue ball travels to the right with speed v.
D．Their
final velocities cannot be determined because momentum is not
conserved in the collision.
E．The
velocities cannot be determined without knowing the mass of each
ball.
