Newton’s Laws of Motion
Newton’s First Law of Motion
If we look for reasons for the above, we realize that objects have some inertia. We have learned that inertia is related to the mass of the object. Newton’s first law of motion describes this very property and is therefore also called the law of inertia. All instances of inertia are examples of Newton’s first law of motion.
Balanced and Unbalanced Force
You must have played tug-of-war. So long as the forces applied by both sides are equal, i.e., balanced, the center of the rope is static in spite of the applied forces. On the other hand, when the applied forces become unequal, i.e., unbalanced, a net force gets applied in the direction of the greater force, and the center of the rope shifts in that direction.
"An object continues to remain at rest or in a state of uniform motion along a straight line unless an external unbalanced force acts on it."
When an object is at rest or in uniform motion along a straight line, it does not mean that no force is acting on it. Actually, there are a number of forces acting on it, but they cancel one another so that the net force is zero. Newton’s first law explains the phenomenon of inertia, i.e., the inability of an object to change its state of motion on its own. It also explains the unbalanced forces which cause a change in the state of an object at rest or in uniform motion.
Newton’s Second Law of Motion
The effect of one object striking another object depends both on the mass of the former object and its velocity. This means that the effect of the force depends on a property related to both mass and velocity of the striking object. This property was termed ‘momentum’ by Newton.
Momentum has magnitude as well as direction. Its direction is the same as that of velocity. In the SI system, the unit of momentum is kg m/s, while in the CGS system, it is g cm/s.
If an unbalanced force applied to an object causes a change in the velocity of the object, then it also causes a change in its momentum. The force necessary to cause a change in the momentum of an object depends upon the rate of change of momentum.
Newton’s Third Law of Motion
Newton's third law of motion states that for every action, there is an equal and opposite reaction. This means that whenever an object exerts a force on another object, the second object exerts an equal and opposite force on the first object.
This law can be observed in various everyday situations. For example, when you push a wall, the wall pushes back with an equal force. When a swimmer pushes the water backward with their arms, the water pushes the swimmer forward.
It's important to note that the action and reaction forces act on different objects and not on the same object. The forces are equal in magnitude but opposite in direction.
Conclusion
Newton's laws of motion form the foundation of classical mechanics and provide fundamental principles for understanding how objects move and interact with forces. The first law explains the concept of inertia, the second law relates force and acceleration, and the third law describes the nature of action and reaction forces.
These laws have applications in various fields, including engineering, physics, and everyday life. By understanding and applying Newton's laws, we can analyze and predict the behavior of objects in motion.
