Angular momentum will not change unless an external torque acts upon the system
The short answer would be that angular momentum is conserved, i.e. it cannot be created nor destroyed.
A more technical answer would be that there is a certain theorem in theoretical physics called Noether's theorem which shows that if a physical theory exhibits rotational invariance (i.e. the physics are the same even if you rotate the system) that angular momentum conservation is a result.
According to particle physics therefore the conservation of angular momentum seems to tell us that the Universe is invariant under rotations. This might seem strange, because surely rotating yourself changes how think look, but the physics involved remains the same.
The Law of conservation of momentum tells us that the law of conservation of energy is in effect. The first derivative of energy is force. If the force is zero, then there is conservation of energy. If force is zero than momentum is constant as force is dP/dt then 0=dP/dt or Conservation of Momentum.
By understanding the law of conservation of angular momentum and by accurately measuring its separation from us.
it tells us food and rain for the conservation
You have more or less described a law of physics known as conservation of momentum, which is not the same thing as the law of universal gravitation. The law of universal gravitation describes the way mass attracts other mass, and the law of conservation of momentum tells us that momentum is neither created nor destroyed. These two laws are not connected.
Using the commutation relation will help us compute the allowed total angular momentum quantum numbers of a composite system.
conservation of matter
Momentum is of two kind. One is linear momentum and the other is angular momentum. Linear momentum is defined as the product of the mass and the velocity. Hence a vector quantity. To change the momentum of a given body with its mass constant, its velocity is to be changed. Velocity change could be made by changing its magnitude or direction or both. Angular momentum is the product of moment of inertial and the angular velocity. Same manner, angular momentum is also a vector quantity as angular velocity is a vector quantity. Most of us think that moment of inertia of a body about any prescribed axis is also a vector quantity. It is totally wrong as far as my approach is concerned. Moment of inertia is a scalar quantity. So to change the momentum, some force can be applied by allowing a moving body to collide with. Angular momentum can be changed by applying torque on it. Torque colloquially saying is a turning force. Moment of effective force about an axis is termed as torque.
It tells us that it doesn't change over time. That's what a "conservation law" says in general - that a certain quantity doesn't change over time.
1) You fire a gun, say. The bullet moves forward, but nature says that the total momentum has to be conserved - so surely there has to be an equal momentum backwards somewhere? And there is - you feel the effect of firing the gun by being jolted backwards.But why does the bullet move so fast and you move so slowly compared to it? Surely they are not balanced? Well - Newton told us that p=mv (momentum is mass multiplied by velocity). The bullet has very little mass, so with a given momentum it has to move really fast. But you have a large mass compared to it - so for the same momentum you only have to move slowly.This is a commonly used consequence of the conservation of momentum.2) Here is a better one (conservation of angularmomentum)You are in a playground; you're in one of those spinny things that children ride around on. When you move to the centre, you find that you start to speed up, rotating faster. When youmove back awayyou slow back down again.Why? Newton says that L = mvr (angular momentum is mass times velocity times radius from the centre of rotation). Therefore if you decrease the radius, you increase either your mass or your velocity to keep momentum conserved. Clearly you are only going to increase velocity.This was my favourite.
Simply because physicists discovered that it is a product that is conserved. In collisions of two objects for example, if you add up the momentum before the collision the momentum will be the same after the collision. Note that momentum is not something that has a concrete reality. A rock sitting on the ground has zero momentum relative to us here on earth but has alot of momentum relative to someone on mars. It can not have zero momentum and alot of momentum at the same time, it depends on ones frame of reference. My point is that momentum is not at 'concrete" thing. Refer to the 'Conservation of linear momentum' in Wikipedia.org, "The World's Encyclopedia" *Check out related links*
As far as we can tell, it doesn't. Momentum is defined as (mass) times (velocity). There appear to be only two ways in which momentum can decrease: either the mass has to magically evaporate, or else the velocity has to decrease. Since mass conservation is a nearly fundamental law of nature, that leaves us with velocity as the only way to change the momentum of a moving body.
Newton's third law of motion is the one related to the transfer of momentum when a bat strikes a ball. His third law of motion tells us that every action has an equal and opposite reaction.