Final answer:
The total momentum after the collision of the two cars, one moving west and the other east, is 10,000 kgm/s straight east, as momentum is conserved and the westward momentum is subtracted from the eastward momentum.
Step-by-step explanation:
The student asked about the total momentum after the collision of two cars moving in opposite directions. Since momentum is a vector quantity, it includes both magnitude and direction. To find the total momentum after the collision, you subtract the momentum of the car moving west from the momentum of the car moving east, because they are in opposite directions. The westward car's momentum is 10,000 kgm/s, and the eastward car's momentum is 20,000 kgm/s.
The total momentum after collision is the vector sum of the two momenta: 20,000 kgm/s (east) - 10,000 kgm/s (west) = 10,000 kgm/s east. This means the correct answer is D. 10,000 kgm/s straight east.