Conservation of Momentum on Inclined and Flat Surfaces

[EverythingIsACircle]

Would momentum be conserved on a cart if in one situation it is on an incline and the other it is on a flat surface(assuming it is pushed)

I am confused because I thought that since gravity is an internal force, it is a conservative force. But then the final velocity of the cart would be higher. Please help I'm in high school who's struggling in physics

 

[Doc Al]

I am confused because I thought that since gravity is an internal force, it is a conservative force.

As far as the cart is concerned, gravity is an external force. Momentum of the cart will not be conserved. (Total momentum of the cart plus incline/earth will be conserved. In that system, gravity is an internal force.)