Answer
The momentum of block 3 is less than the initial momentum of block 1
Work Step by Step
We can find an expression for the initial momentum of block 1:
$p_1 = m_1~v_1$
$p_1 = m_1~(4.00)$
$p_1 = 4.00~m_1$
In part (a), we found that the speed of block 3 is $7.11~m/s$
Note that $m_3 = 0.25~m_1$
We can find an expression for the momentum of block 3:
$p_3 = m_3~v_3$
$p_3 = (0.25~m_1)~(7.11)$
$p_3 = 1.78~m_1$
The momentum of block 3 is less than the initial momentum of block 1
