# Exploring Conservation of Momentum and Energy

In summary, the law of conservation of momentum is closely related to the law of conservation of energy and both stem from Newton's laws. While energy is a scalar quantity and momentum is a vector, momentum is often easier to track and conserve in certain situations, such as inelastic collisions. However, in reality, energy is always conserved but may be lost as heat or deformation, making it more difficult to identify in problem-solving scenarios. Ultimately, the conservation of momentum is supported by Newton's 3rd law.
Is the law of conservation of momentum underpinned by the law of conservation of energy?

No . They both follow from Newtons laws at the most basic level. Also note that Energy is a scalar quantity and momentum is a vector, so there is quite a bit of difference in the kind of information they provide.

also, momentum is sometime more easy to keep track of, than energy. So in some situations we use a physical model where energy is not conserved, but momentum is conserved. For example, inelastic collisions, where we say momentum must be conserved, but we do not require energy to be conserved. In reality, the energy is lost as heat and deformation of the objects. But since it is hard to keep track of those things, we often just model the situation as if it does not conserve energy.

BruceW said:
also, momentum is sometime more easy to keep track of, than energy. So in some situations we use a physical model where energy is not conserved, but momentum is conserved. For example, inelastic collisions, where we say momentum must be conserved, but we do not require energy to be conserved. In reality, the energy is lost as heat and deformation of the objects. But since it is hard to keep track of those things, we often just model the situation as if it does not conserve energy.

Nice example of this:

A.T. said:
Nice example of this: ...
haha, yeah I saw that. It felt nice to guess the right answer straight away. I suppose it is the intuition that comes from doing these kinds of problems many times. Momentum is more important than energy, when it comes to these types of problems. Again, I feel the need to say energy is 'truly' conserved too. But it's lost as heat or deformation, which is not easy to identify in these kinds of problems.

underpinned by Newton's 3rd law.

## 1. What is conservation of momentum and energy?

The conservation of momentum and energy is a fundamental principle in physics that states that the total momentum and energy in a closed system remains constant over time, regardless of any internal changes or external forces acting on the system.

## 2. How does conservation of momentum and energy apply to everyday life?

The conservation of momentum and energy applies to everyday life in many ways, such as when playing sports or driving a car. For example, when a person hits a baseball with a bat, the momentum and energy of the bat is transferred to the ball, causing it to move. In a car, the conservation of momentum and energy is evident when the brakes are applied and the car comes to a stop.

## 3. What are some examples of systems where conservation of momentum and energy is observed?

Some examples of systems where conservation of momentum and energy is observed include collisions between objects, pendulums, and oscillating systems. It also applies to larger systems, such as planets orbiting around the sun, where the total momentum and energy of the system remains constant despite the gravitational forces acting on the objects.

## 4. What happens when conservation of momentum and energy is not observed?

When conservation of momentum and energy is not observed, it usually means that there is an external force acting on the system or that energy is being lost due to friction or other factors. This can result in changes in the system's momentum and energy, leading to unexpected or unpredictable outcomes.

## 5. How is conservation of momentum and energy related to the laws of thermodynamics?

The laws of thermodynamics, specifically the law of conservation of energy, are closely related to the conservation of momentum and energy. Both principles state that energy cannot be created or destroyed, only transferred or converted from one form to another. In thermodynamics, this applies to systems undergoing thermal or chemical processes, while in momentum and energy conservation, it applies to all systems.

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