momentum change

[Xamfy19]

i need help for this question. i don't know if i got it right or wrong:

a compact car and a large truck collide head on and stick together. which undergoes the larger momentum change?

i thought the answer is "can't tell without knowing the final velocity of the combined masses." Am i correct?

[Doc Al]

Originally posted by Xamfy19
i thought the answer is "can't tell without knowing the final velocity of the combined masses." Am i correct?
No. Total momentum is conserved during the collision. Think about what that means.

[Xamfy19]

That means both of them undergone same momentum change. If I am wrong, please let me know. Thanks again, Doc

[Doc Al]

Originally posted by Xamfy19
That means both of them undergone same momentum change. If I am wrong, please let me know.
Each undergoes the same magnitude of momentum change. (The changes are equal and opposite, of course.)