Brian is trying to pull Julie on a sled across a flat snowy field. Brian pulls on a rope attached to the sled. Brian's pulling force is directed forward and upward at a 30 degree angle above horizontal. Julie's mass is 50 kg, and the sled is 8 kg. If the coefficient 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?