As shown below, a cart weighing 300 N loaded with 500 N of coal was rolling along a track with almost no friction. A child on a bridge 10 m above the track thought it would be fun to drop something into the cart. The child's timing was perfect, and a 5 kg sack of flour fell straight down into the cart and broke open upon impact. Flour went everywhere and coated the coal so that it looked like the cart was carrying a load of chalk. What was the effect on the velocity of the cart?