As we discussed in previous blog, the first law of motion indicates that when an unbalanced external force acts on an object, its velocity changes, that is, the object gets an acceleration. From our everyday life observation, we know that, during the game of table tennis if the ball hits a player, it does not hurt him. On the other hand, when a fast-moving cricket ball hits a spectator, it may hurt him. A truck at rest does not require any attention when parked along a roadside. But a moving truck, even at very low speeds, may harm a person standing in its path. A small mass, such as a bullet may kill a person when fired from a gun. These observations suggest that this kind of impact is produced by combination of mass and velocity in the object. In the language of physics, this combination of mass and velocity is known as momentum. Momentum is defined as the product of mass and velocity of an object possessing a magnitude and a direction. It is denoted by ‘P’ and mathematically expressed as:
p = mv.
This property of an object was introduced by Newton in his book principia published in 1687. He introduced this property under his second low of motion.
The second law of motion states that the rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of force. In other words, this can by stated as, higher the force is applied, higher momentum will be and lower the force is applied, lower the momentum will be. Mathematically this law is expressed as force is equal to derivative of momentum with respect to time and it is simplified as force is equal to mass multiplied by acceleration.
F = ma
In Newtonian mechanics, momentum is also subdivided into two categories, linear momentum, and transitional momentum. We will discuss about these in our advanced blog.
