As jack pulls his wagon down the street it moves faster and faster. jill, sitting a few meters ahead on the sidewalk, wants to slow jack's wagon down so that it travels with a constant speed. how can jill accomplish her goal? a) sit in the wagon so that it begins to slow down. b) push jack away from the wagon so that he is no longer pulling it. c) pull on the wagon in the opposite direction with twice jack's force. d) pull on the wagon in the opposite direction with a force equal to jack's.