16. Brian is trying to pull Julie on a sled across a at, snowy field. Brian pulls on a rope attached to the sled. His pulling force is directed forward and upward at an angle of 30 above horizontal. Julie's mass is 50 kg, and the sled's mass is 8 kg. If the coefcient of static friction between the sled runners and the snow is 0.10, how much force must Brian exert on the rope to start moving the sled