Answer:
Zero
Explanation:
The momentum of an object is a vector quantity given by
[tex]p=mv[/tex]
where
m is the mass of the object
v is its velocity
Being a vector, momentum has also a direction, which is equal to the direction of the velocity.
In this problem, we have two balls of equal mass, so
[tex]m_1=m_2=m[/tex]
And they have the same speed: this means that the magnitude of their velocity is the same, but their direction is opposite, so
[tex]v_2=-v_1[/tex]
Therefore, the momentum of ball 1 is
[tex]p_1=m_1 v_1 = mv_1[/tex]
While the momentum of ball 2 is
[tex]p_2=m_2 v_2 = m(-v_1)=-mv_1[/tex]
Therefore, the total momentum before the collision is
[tex]p=p_1+p_2=mv_1-mv_1=0[/tex]
Because the two balls have same momentum but in opposite directions.
