An inventive child wants to reach an apple in a tree without climbing the tree. Sitting in a chair connected to a rope that passes over a frictionless pulley (see figure), the child pulls on the loose end of the rope with such a force that the spring scale reads 280 N. The child's true weight is 319 N, and the chair weighs 160 N. The child's feet are not touching the ground. A (a) Show that the acceleration of the system is upward. (Submit a file with a maximum size of 1 MB.) Choose File No file chosen This answer has not been graded yet. Find its magnitude (in m/s2). m / s 2 (b) Find the force (In N) the child exerts on the seat of the chair. N