A moving rail car collides with a stationary car that has identical mass, and the two cars begin to move together. If the momentum of the moving car was 450,000 kg•m/s, what is the total momentum of the two cars after the collision? A. 225,000 kg•m/s
B. 450,000 kg•m/s
C. 900,000 kg•m/s
D. Total momentum cannot be determined from this information.

the best answer for these questions would be:

1.            c. is smaller

2.            d) concrete operational

3.            b) interaction with the environment – the children interact with their environment can them learn more.

4.            a) parents who reason openly with children can limit a child’s cognitive ability.

i think its d if wrong im sorry