before colliding, the momentum of block A is +15.0 kg*m/s, and Block B is -35.0 kg*m/s. After, block a has a momentum -12.0 kg*m/s. What is the momentum of block B afterwards?
\(\text{in a frictionless system linear momentum is conserved}\\ 15.0 + (-35.0) = (-12.0) + m_{bf}\\ m_{bf} = -8 kg*m/s\)
