a child causes a wagon to accelerate by pulling it with a horizontal force.
newton's third law says that the wagon exerts an equal and opposite force on the child. how can the wagon accelerate
The wagon can accelerate despite exerting an equal and opposite force on the child due to the difference in their masses. According to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
In this scenario, when the child pulls the wagon with a horizontal force, the wagon experiences a forward force. As a result, the wagon accelerates in the direction of the applied force. However, the wagon also exerts an equal and opposite force on the child, as stated by Newton's third law.
The acceleration of the system (child + wagon) depends on the difference in their masses. Since the mass of the wagon is typically much larger than the mass of the child, the resulting force on the system is directed mostly towards the wagon. As a result, the wagon accelerates more than the child, despite exerting an equal and opposite force on the child.
The wagon accelerates when a child pulls it due to the principles of Newton's second law of motion. According to Newton's second law, the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. The net force acting on the wagon is the difference between the force applied by the child and any resistive forces, such as friction.
When the child applies a horizontal force on the wagon, the wagon exerts an equal and opposite force on the child, as described by Newton's third law. However, this action-reaction pair does not affect the acceleration of the wagon directly. Instead, it impacts the child's motion.
The child's force on the wagon creates an unbalanced force, or net force, causing the wagon to accelerate. This acceleration is determined by the magnitude of the force applied by the child and the mass of the wagon. The larger the applied force or the lighter the wagon, the greater the acceleration will be.
It's important to note that Newton's third law describes the action-reaction pair between the wagon and the child, but it does not directly explain the acceleration of the wagon. The acceleration is a result of the net force acting on the wagon, which is influenced by the applied force and any resistive forces like friction.
The net force ON the wagon is the force exerted by the child on the handle (minus the drag of the wheels and any air friction but that is not mentioned here).
Forces exerted BY the wagon do not count in the SECOND law which is the Net force ON the object equals the rate of change of momentum which is the mass times the acceleration.
F = m A
where F = net force ON the object