A box fails to slide down a ramp at a warehouse. What happens if you put the box on a cart that has wheels?

If the box is placed on a cart with wheels, the friction between the box and the ramp is replaced by the rolling friction between the wheels and the floor. This reduces the resistance and allows the box to move more easily down the ramp. The wheels on the cart reduce the surface area in contact with the floor, decreasing friction and enabling movement.