Answer
The mass of the second cart is $~~98.7~g$
Work Step by Step
We can use Equation (9-67) to find the mass of the second cart:
$v_{1f} = \frac{m_1-m_2}{m_1+m_2}~v_{1i}$
$v_{1f}~(m_1+m_2) = (m_1-m_2)~v_{1i}$
$m_2~(v_{1i}+v_{1f}) = m_1~(v_{1i}-v_{1f})$
$m_2= \frac{m_1~(v_{1i}-v_{1f})}{v_{1i}+v_{1f}}$
$m_2= \frac{(340~g)~(1.2~m/s-0.66~m/s)}{1.2~m/s+0.66~m/s}$
$m_2 = 98.7~g$
The mass of the second cart is $~~98.7~g$
