Object A has momentum +12 kg·m/s (rightward). Object B has momentum -8 kg·m/s (leftward). What is the total momentum of the two-object system?
A+20 kg·m/s
B+4 kg·m/s
C−4 kg·m/s
D20 kg·m/s (with no direction)
Explanation
📌 Momentum is a vector — sum values with signs: +12 + (−8) = +4 kg·m/s. Positive means the total is rightward. Distractor A added magnitudes without signs; C got the sign wrong (would represent A moving left, B right); D ignores that momentum is a vector and needs direction.