10. Two forces act on an object. The first force pulls 400 N to the east while the second force pulls 600 N to the west. The object accelerates 5.00 m/s to the west. Determine the mass of the object. [40.0 kg] 11. According to Newton's Third Law, forces always come in pairs: action and reaction. Identify the reaction force for each force listed below. [Appendix A] a. The weight of a book pushes down on a horizontal surface. b. The force due to gravity acts on a ball causing it to accelerate downwards. A boy applies a force by pushing on a wall. 12. Rochelle places a 10.0 kg object on a horizontal surface. Determine the normal force acting on this object if she a. is not touching it. [98.1 N] b. presses down with a force of 40.0 N. [138 N] up knoxhol s anois bellug ei bale / 0.8 7 13. Zoe applies a horizontal force of 120 N to the east on her 10.0 kg toboggan causing it to accelerate at 2.00 m/s to the east. Determine the force of friction opposing the toboggan's motion. [100 N, west] required to be