[dabibibff]

Really? Hmmm, obviously confused then. I thought friction increased with velocity (not a lot, but a little).

In that case, then, if you add some force beyond that of friction, the cart will continue accelerating and never reach equilibrium, unless you factor in air resistance (drag).

Kinetic friction is proportional to the contact surface, the weight of the object 'above' and the chemical bonding between the surfaces.
It has nothing to do with velocity.

For drag... well it's a little more complex, it depends on linear or turbulent flux, blah-blah-blah...