Explanation:
Given that,
Mass of the cart, 
Mass of the cart 2,
Final speed of cart 2, 
Final speed of cart 1 is 0 as it comes to rest.
Let us assume that the initial velocity of the cart 2 is 0. So using the conservation of linear momentum as :

So, the initial velocity of the 1.0-kg cart is 0.9 m/s.
Answer:
answer is friction. MCQ A is answer
Not sure if this is what your looking for, but hope it helps. Nitrogen gas can be changed into nitrogen compound through nitrogen fixation, which is the conversion of nitrogen gas to ammonia, that are absorbed by the plant to make protein. Another way is through animals eating plants and obtaining nitrogen, which is later released, by decomposes, when the organism dies.