My classmates and I were discussing the impulse-momentum theorem and how they correlate. The example problem consisted of two cars running into solid surfaces at the same velocity. One car ran into a brick wall and came to a complete stop. The other car ran into a haystack and came to a complete stop. This was done so to where the change in momentums were the same between the two cars. A question was then arisen as to whether the impulse of the two surfaces were the same, as impulse and momentum are considered to always be equal to each other mathematically. My teacher began to say that the impulses were different because the surfaces were different, however, I stated that if the change in momentums were equal between the two cars, then the impulses between the two cars would also be the same. Who's right?