Force and Laws of Motion
Force is a push or pull that can change the state, shape, size or velocity of an object. Forces can be broadly divided into balanced and unbalanced forces. If the resultant of all the forces acting on an object is zero, then the forces are called balanced forces. If the resultant of all the forces acting on an object is non-zero, then the forces are known as unbalanced forces. Only the unbalanced forces can change the state of rest or motion of an object. The motion of the objects is governed by the Newton’s three laws of motion.
First law of motion states that an object remains in its state of rest or of uniform motion in a straight line, unless an unbalanced force acts on it. It is also known as the law of inertia. Second law of motion states that the rate of change of momentum of an object is proportional to the force applied on it and the change takes place in the direction of force. According to the third law of motion, to every action, there is an equal and opposite reaction. The action and reaction forces are equal in magnitudes but they act on different bodies. These three laws have many applications in daily life.
In an isolated system, there are no external forces. In such a case, the total momentum of the system remains conserved. This is known as the law of conservation of momentum.