Conservation of Energy vs Momentum | Conservation of Momentum vs Conservation of Energy
Conservation of energy and conservation of momentum are two important topics discussed in physics. These basic concepts play a major role in fields such as astronomy, thermodynamics, chemistry, nuclear science and even mechanical systems. It is vital to have a clear understanding in these topics in order to excel in these fields. In this article, we are going to discuss what conservation of energy and conservation of momentum are, their definitions, applications of these two topics, the similarities and finally the difference between conservation of momentum and conservation of energy
Conservation of Energy
Conservation of energy is a concept that is discussed under classical mechanics. This states that the total amount of energy in an isolated system is conserved. However, this is not entirely true. To understand this concept fully, one must first understand the concept of energy and mass. Energy is a non-intuitive concept. The term “energy” is derived from the Greek word “energeia”, which means operation or activity. In this sense, energy is the mechanism behind an activity. Energy is not a directly observable quantity. However, it can be calculated by measuring external properties. Energy can be found in many forms. Kinetic energy, thermal energy and potential energy are to name a few. Energy was thought to be a conserved property in the universe up until the special theory of relativity was developed. The observations of nuclear reactions showed that the energy of an isolated system is not conserved. In fact, it is the combined energy and mass that is conserved in an isolated system. This is because energy and mass are interchangeable. It is given by the very famous equation E = m c2,where E is the energy, m is the mass and c is the speed of light.
Conservation of Momentum
Momentum is a very important property of a moving object. The momentum of an object is equal to the mass of the object multiplied by the velocity of the object. Since the mass is a scalar, the momentum is also a vector, which has the same direction as the velocity. One of the most important laws regarding momentum is Newton’s second law of motion. It states that the net force acting on an object is equal to the rate of change of momentum. Since the mass is constant on non-relativistic mechanics, the rate of change of momentum is equal to, the mass multiplied by the acceleration of the object. The most important derivation from this law is the momentum conservation theory. This states that if the net force on a system is zero, the total momentum of the system remains constant. Momentum is conserved even in relativistic scales. Momentum has two different forms. The linear momentum is the momentum corresponding to linear movements, and the angular momentum is the momentum corresponding to the angular movements. Both of these quantities are conserved under the above criteria.
What is the difference between conservation of momentum and conservation of energy?
• Energy conservation is only true for non-relativistic scales, and provided that nuclear reactions do not occur. Momentum, either linear or angular, is conserved even in relativistic conditions.
• Energy conservation is a scalar conservation; therefore, the total energy amount must be considered when doing calculations. Momentum is a vector. Therefore, momentum conservation is taken as a directional conservation. Only the momenta on the considered direction have an impact on the conservation.