The state of motion of an object is affected by the forces acting on it. The book is at rest because the net force (sum of all external forces acting on it is zero (0). When the net force acting on a system is zero, it means that the external forces are balanced. This means that the object is either at rest or at constant motion. Forces can balance each other if they act on the same system. If, however, the forces are acting on two different systems, they will not cancel each other. q) Observe the forces in figure 4. Do action-reaction forces act on the same system? 1) Can we say that the action-reaction forces cancel each other? Why? s) Describe Newton's third law of motion using all the key points in this activity.
Answer:An object with no net forces acting on it which is initially at rest will remain at rest. If it is moving, it will continue to move in a straight line with constant velocity. Forces are "pushes" or "pulls" on the object, and forces, like velocity and acceleration are vector quantities.
