Acart is set rolling across a level table, at the same speed on every trial. if it runs into a patch of sand, the cart exerts on the sand an average horizontal force of 6 n and travels a distance of 6 cm through the sand as it comes to a stop. if instead the cart runs into a patch of gravel on which the cart exerts an average horizontal force of 9 n, how far into the gravel will the cart roll before stopping? (a) 9 cm (b) 6 cm (c) 4 cm (d) 3 cm (e) none of those answers