1) A stone has been thrown straight upwards, and as it rises, the gravitational force exerted on it by the Earth causes it to slow down. Describe this interaction between the stone and the Earth in terms of impulse and momentum

2) Two identical carts are rolling towards each other on a level track, both at exactly the same speed. Explain why the total momentum of the two carts is zero, even though both of them are moving.

Note: no collision occurs in this question!

3.)Continuing the previous question: if the carts subsequently collide, one possible outcome (there are many others) is that both of them end up at rest immediately afterwards. Explain why this outcome doesn't violate the momentum conservation principle.

**Subject Physics Mathematical Physics**