Two cars collide at an intersection. one car has a mass of 900 kg and is moving 10 m/s to the north, while the other has a mass of 1000 kg and is moving 7 m/s to the south. what is their combined momentum?

2000 kgm/s to the north.  

Explanation:

For any   colliding bodies, momentum must be conserved.

In this case we are required to find the momentum before collision.

Since the two cars are moving to different direction, we are going to take one velocity as negative.

∴ (900×10) + (1000× -7) = 9000 + - 7000

                                       = 9000 - 7000

                                       = 2000 kgm/s

Since the answer is positive and we had taken the velocity due north as positive, the combined momentum is 2000 kgm/s to the north.  

the earths atmosphere is made up of nitrogen and oxygen. solids can turn into gasses through a process called sublimation. sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.

hope this : d

i think the answer is a, hope this : )