Charlie is playing with his daughter torrey in the snow. she sits on a sled and asks him to slide her across a flat, horizontal field. charlie has a choice of (a) pushing her from behind by applying a force downward on her shoulders at 30^\circ below the horizontal (fig. a), or (b) attaching a rope to the front of the sled and pulling with a force at 30^\circ above the horizontal (fig. b). which would be easier for him and why?